The India craton is a separate geotectonic unit, which is located in the south of the Himalayas piedmont fault and presently connected with the Eurasian continent. It is mainly composed of seven Archean micro-continents, including Aravalli, Bundelkhand, Singhbhum, Bastar, Eastern Dharwar, Western Dharwar and the southern granulite, and two Proterozoic mobile belts, Satpura and Eastern Ghats. In this paper we summarize the geological characteristics of the main tectonic units of the India craton based on the latest project research results. The stable configuration of the India craton was largely completed at 2.50 Ga. The India craton metamorphic crystalline basement is mainly composed of TTG gneiss, granite, and metamorphic series. The cover of the India craton is mainly composed of the shallow marine clastic sedimentary rocks and platform carbonate rocks, depositing in the Proterozoic sedimentary basins, such as the Vindhyan, Chhattisgarh, Cuddapah, Godavari, Indravati, and Bhima-Kaladgi basins.

A comprehensive research on the Archean metamorphic buried-hill in the central area of Damintun depression was conducted on well log, seismic, core description and rock-mineral analysis. Based on the study, the metamorphic rocks are very complicated, including 3 kinds and 18 rock species, such as migmatitic granite, migmatitic gneiss, migmatite, amphibole plagiogneiss, leptite, amphibolite, granulite and rich inhomogeneous basic dike rock and cataclasite and so on; and the metamorphic sequence is composed of several belts of lithological combination, and the metamorphic rocks are composed by several petrological sections vertically (from down to top), including migmatitic granite section, migmatitic granite and migmatitic gneiss interbedded with amphibolite and dolerite section, migmatite and granulite section, leptite and gneiss section and crust of weathering. The petrology is also plane dividable. The metamorphic rock is a non-uniform massive body. The low porosity and low permeability reservoir of Archean metamorphic fractured reservoir is mainly controlled by petrology and mineralogy. The cataclastic granulite, leptite, migmatitic granite and gneiss could be the perfect reservoir. The study results help to detect the petrological, spatial distribution and influence of lithology on reservoir that will be beneficial for further petroleum production and exploration; also, the study will complete and enrich the theory of inner basement hydrocarbon accumulation.

This paper focuses on the study of fluvial facies isochronous stratigraphic division based on a medium cycle flood surface. Under the guidance of the high resolution sequence stratigraphy theory, based on the flood surface of a middle period cycle, the stratigraphic division of river facies were divided and contrasted according to the elevation difference on the top of channel sand bodies in different periods. Taking the N₂m² oil group in the lower section of the Minghuazhen Formation in the north part of the Bohai Q oilfield as an example, the authors established a set of methods for fluvial facies isochronous stratigraphic division based on the sand body development frequency and elevation difference. According to the comprehensive analysis of seismic facies, logging facies,and sandstone development characteristics, the downcut position of the later channel was identified. As a basis of isochronous stratigraphic division, the original flooding mudstone interface at the end of the medium-term cycle was restored after backfilling the part that had been eroded. According to the frequency characteristics of sand body development, and elevation relationship between a sand body top surface and a medium cycle flood surface, the equal time interface recognition curves were constructed. These curves are used to characterize the concentrated development positon of mudstone and to identify the isochronous interfaces of short or ultra short cycles. Based on the above work, the isochronous stratigraphic division is realized. A case analysis shows that this method can idendify the interface positions between different stratigraphic elements effectively in dividing the N₂m² oil group into six isochronous units, and the sedimentary characteristics of river courses in six periods conform to the sedimentary evolution pattern of the middle term base level rising semi-cycle.

Due to the complexity of the formation mechanism of the turbidite reservoir, five principal factors were extracted through analysis on 13 parameters for reflecting the petrophysical, microscopic pore structural, sedimentary and heterogeneity characteristics of the reservoir. Then using the five principal factors as the input,the flow unit prediction model was established based on the support vector machine method. The model was used to test the predicting samples in Fan 29 block of Daluhu oilfield,and the accuracy rate of the results reached 90.38%.With the established prediction model, the flow unit of the single sand bed 4⁴¹ in the study area was classified and evaluated, the prediction results were highly consistent with the qualitative analysis results. The flow unit classification well corresponded to the distribution of the sedimentary microfacies as the follows:the I-type and Ⅱ-type flow-units are the best quality reservoirs,that are developed only in the turbidity channel and lobe;the flow-unit of Ⅲ-type is widely distributed in the turbidity channel, channel edge,and the edge of middle fan;and the flow-unit IV is distributed in the edge of the fan. The studies suggest that the prediction model of flow units can be more comprehensive in consideration with the complex mapping relationship between the various geological factors and the flow units.

Aiming at the difficulty in obtaining the key parameters and the doubtful reliability of the existing quantitative characterization method for braided river reservoir architecture units, based on the theory of reservoir architecture on single braided channel width, a new method is proposed. Firstly, based on the analysis of single well reservoir architecture units, the horizontal distribution of coeval braided river channels is determined. Secondly, the single braided river channels are set up, and their width can be measured through connecting-well profiles perpendicular to the paleo-current direction. Thirdly, according to the new quantitative model, the width of braided water channel and the length and width of a complex channel bar are calculated. Lastly, in a single braided channel, the plane distribution of four-stage configuration units is determined, and then the compound channel bar is dissected in the dense well network area to determine the location and geometry of the single channel bar. The new method is applied to evaluate the scale of the reservoir architecture units of the braided river tight sandstone gas field of the 1-3 layer of the lower part of 8th member of the Xiashihezi Formation in the Su××EOR test area. It is shown that five single braided river channels are developed in the 1-3 layer of the 8th member within the width of 1 050 m-1 890 m, a braided channel width of 234 m to 435 m;the length and width of a compound channel bar are 1 931-3 569 m and 685-1 242 m respectively,while those of a single channel bars are 660-1 880 m and 310-1 030 m respectively.

The Luozuoshan gold deposit is located in the north-center of Jiamusi massif of Eastern of Xingmeng orogenic belt, which is a large deposit in the Jiamusi gold metallogenic area. The ore bodies are hosted in the NW and NWW trend extension fractures and the contact zone between the granite and calcareous marble and gneiss, and the mineralization is closely associated with skarn. According to the field and laboratory studies, the authors divided the mineralization process into five stages, i. e, skarn, oxide, early sulfide, late sulfide, and quarts-calcite stages. The inclusion petrography shows that the fluid inclusions are mainly composed of daughter-crystal bearing inclusions, gas-liquid inclusions (incl. rich liquid and rich gas inclusions), pure liquid inclusions, and pure gas inclusions. The measured temperatures indicate that the homogeneous temperatures were 448-462℃, 240-509℃, 166-480℃, 118-360℃, and 57-230℃ from early to late respectively. The salinities of mineralization were w(NaCl)9.21%-10.37% in skarn stage, 1.73%-13.77% in oxide stage, 1.73%-23.71% and 23.64%-39.66% in early sulfide stage, 3.05%-6.44% in late sulfide stage, and 1.73%-11.95% in quarts-calcite stage. During the oxide stage, the initial ore-forming fluid was of high temperature, low-medium salinity, and rich in CO₂, H₂O and a little CH₄. The fluid boiled, resulting in the escape of CO₂ and formation of magnetite. The fluid continued to boil at the early sulfide stage, which caused the increase of pH value, the transformation of the fluid from oxidation to reduction, and the deposition of gold and arsenopyrite. With the temperature decrease at the late sulfide stage, the low temperature minerals precipitated, such as galena, sphalerite, and gold. It is presumed that the Laozuoshan gold deposit is a skarn type gold deposit.

Located in the Archean granite-greenstone belt, the Shujigou copper-zinc deposit belongs to the volcanic-associated massive sulfide deposit (VMS). In this study, the authors carried out a comprehensive study including zircon U-Pb dating, petro-geochemical investigation, and Hf isotope analysis of the biotite plagioclase hornblende gneiss from the Shujigou copper-zinc deposit output. The LA-ICP-MS zircon U-Pb chronology indicated that the biotite plagioclase hornblende gneiss was formed at ca. (2 549.4±5.6) Ma, representing approximately the ore-forming age. Geochemically, the biotite plagioclase gneiss is characterized by its LREE enrichment, HREE depletion, and also the LILEs enrichment and HFSEs depletion, and the original rocks were of a set of island arc environment volcanic-sedimentary assemblage. According to the zircon Hf isotope analysis, the ε_Hf(t)values of biotite plagioclase gneiss are 5.0-8.7, and the single stage model age (T_DM1) varies from 2 527 Ma to 2 649 Ma. These characteristics suggest that the primary magma was derived from a depleted mantle, and the Shujigou area occurred in crustal growing during the Late Neoarchean. Combined with the geochemical characteristics and the evolution of the host rock, the mineralization involved in partial melting of the mantle and forming of a rich base metal magma, and went through plate subduction, magma migration, convergence and eruption til the formation of base metals igneous rocks in the study area. The percolation of seawater down into these igneous rocks and leaching the metals from them into feeder zones formed the VMS deposit system. The fluids within this feeder system were erupted at the seafloor; these magmas focused along the faults, and the minerals were precipitated at the contact zone between these metal-laden fluids and the bottom cold seawater, and subsequently underwent the metamorphism and deformation.

The Xiangshan uranium ore-field is the largest volcanic uranium ore-field in China, its ore-hosting rock is mainly of rhyodacite and porphyroclastic lava with a small amount of the Precambrian metamorphic rocks and Mesozoic granite porphyry. The porphyroclastic lava sub-facies yielde spherical tourmaline nodules with diameters of 10-20 cm, in which the main mineral assemblage is of tourmaline, quartz and minor feldspar, mixed with a small amount of uraninite. Tourmaline alterated early formed feldspar. A detailed mineralogical study for the tourmaline in porphyroclastic lava of the Ruyiting area in Xiangshan was performed by means of the microscope, electron probe, laser ablation multi-collector inductively coupled plasma mass spectrometry. The electron microprobe analysis shows that the tourmaline in porphyroclastic lava is the typical schorl characterized by the enrichment of Na, Fe. The volatile components are high in the tourmaline, of which the content of B₂O₃ is 9.38%-10.04%, and F is 0.10%-1.77%. The high volatile components such as B and F in ore-forming fluid with high oxygen fugacity in early stage of magma evolution made the U element more actively to form complex, which is more conducive to U migration and enrichment. The analysis of boron isotope in tourmaline from two porphyroclastic lava samples was performed by means of in-situ microanalysis of boron isotopes (LA-MC-ICP-MS). The results show that the content of δ¹¹ B in tourmaline is (-13.15±0.72) ‰-(-12.28±0.63) ‰ with the mean value of (-12.72±0.94) ‰; which indicates that the Xiangshan volcano intrusive complex mainly comes from the partial melting of the Xiangshan crustal basement rocks.

The Dongping Pb-Zn deposit,located in the southwest edge of Yangtze platform in the northeastern Yunnan, is a representative deposit with low research and exploitation. In the shape of vein and layer, the orebodies mainly occur in dolomites of the Sinian Dengying Formation, and are obviously controlled by the fractures and their Si/Ca surfaces. The major ore minerals are galena and sphalerite. The wall-rock alteration includes silicification, dolomitization, pyritization. The δ³⁴S‰ value of the sulfides implies that the sulfur was likely derived from seawater and went through a series of thermal chemical sulfate reduction (TSR). The lead isotopic composition of sulfides indicates an extremely radiogenic feature similar to that of the crust. The mineralization is characterized by multiple stages of ore-forming evolution and overlapped by late fluids. A great amounts of lead were formed in the major metallogenic stage with a little zinc formed in the early stage. The near halo Pb, Zn components in borehole S5ZK001→ZK001→S4ZK001 are distributed from shallow to deep from the south-west to the north-east, the same as with those of the borehole ZK001→ZK701-1→ZK1701→ZK3901. With ZK001 as the center, the ore bodies have a bigger buried depth in the south-east and north-east parts of it. There is a certain prospecting potential in the deep part of the north-east (S4ZK001) and the south-east (ZK3901).

The dolomitic breccia strata is drilled in Well PSBX1, Maigaiti slope, Tarim basin. Its age is determinated based on the data of thin section, paleontology sporopollen, isotope, platinum group elements and outcrop profiles. The results show that the 6 884-7 068 m well interval belongs to the Paleogene Tuyiluoke Group, which has very few fossils, 7 068-7 150 m well interval belongs to the Upper Cretaceous Yigeziya Group, which has a lots of sporopollen fossils. The Paleogene-Cretaceous boundary of this well lies at 7 068 m with an abrupt difference in carbon isotope, indicating a dramatic change of marine environment, which can be compared with the global K/E boundary. At this depth, the platinum group elements has obvious anormalies, their contents increase significantly, especially Rh, Ru, Ir, Os and so on. Through this determination, we have enriched our uderstanding of the sedimentary pattern of the Markit slope during the Late Cretaceous to the Early Paleogene.

In order to explore the mechanical properties and mechanisms of saturated sands under different normal stresses, shearing rates and pore water pressures, a continuous large displacement shear test was conducted by using a large ring-shear test apparatus. The research results demonstrated that:1) Given continuous fast shearing, the shearing mechanical properties of sands changed differently under dry, non-drainage and drainage conditions. The saturated sands presented certain strain softening under the non-drainage condition. 2) In the ring-shear test with the same positive stress and shearing rate, the shear strengths of the saturated sands differed significantly under the different drainage conditions (upper drainage, down drainage and up-down drainage). 3) Under the drainage conditions in the ring-shear test, the difference between shearing stress and strength of sands was not only related with the fine particle movement and structural changes, but also influenced and controlled by the variations of the pore water pressure in the shearing process. 4) Given drainage ring-shearing, the dissipation of pore water pressure of saturated sands was related with the smoothness of the drainage channels formed in the soil under the different drainage modes, and influenced by different shearing rates and normal stress.

In order to verify that the groundwater level and slope stability can be effectively controlled in an actual landslide by intercepting water with compressed air, based on the analysis of the characteristics and the formation mechanism of landslide deformation and failure, taking the Xiaodan landslide as an example, the authors studied the effectiveness of the intercepting water with compressed air applied in the treatment of this kind of landslide. Through a two-dimensional finite element numerical simulation, the variation law of a slope stability under different inflation pressures was analyzed. It is found that by inflating air into the appropriate edge of a landslide, a stable unsaturated water cut curtain can be formed to reduce the groundwater level in the potential slide area. When the inflation pressure is 125 kPa, which is the optimum inflation pressure of Xiaodan landslide, the stability coefficient increases from 1.144 to 1.209 under unexploited condition; while the stability coefficient increases from 1.106 to 1.139 under excavated condition. When the infiltration from the trailing edge increases during the rainy season, the effectiveness of intercepting water with compressed air is more significant for landslide stability.

Since 1980s, the over-exploitation of groundwater has caused a significant and persistent decline of water levels in some areas of the three coastal cities of north Jiangsu (Lianyungang, Yancheng, and Nantong), land subsidence, water salinization, and other issues. Based on the previous study and the boreholes and water level observation data from 2005 to 2013, the authors established a three dimensional heterogeneous anisotropic groundwater flow numerical model. It can truly calculate the evolution of groundwater flow field in this area after calibration and verification. The groundwater flow was simulated between 2005 and 2013, and the calculated results fitted the observation data well for every observation well. The simulation results of water level and water balance showed that the decreases of groundwater levels of every confined aquifer were effectively controlled through reducing the groundwater exploitation, although the groundwater in this area was still in the state of over exploitation. In consideration with the requirement of controlling geological environment disasters including salt water diffusion and land subsidence, the model predicted and compared the evolution of deep groundwater flow fields (including the confined aquifers Ⅱ, Ⅲ and Ⅳ) under two different exploitation strategies until 2020. The predictions revealed that the decreases in groundwater levels of every confined aquifer under two strategies were well controlled. Especially with the control exploitation strategy, the average decreasing rates of the confined aquifers Ⅱ, Ⅲ, Ⅳ were 0.15, 0.16 and 0.15 m/a respectively, which were reduced by 46.43%, 65.21% and 48.28% comparing with that in the simulated period in this study. The negative variation rate of storage volume under the lowest pumping intensity suggests that it is necessary to further reduce the exploitation of groundwater.

In order to investigate the potential human health risk of groundwater contamination in the Jinghui irrigation district in Shaanxi Province, the samples of groundwater were collected, and their physical and chemical characteristics were analyzed through laboratory test. The contamination was evaluated by using a single factor index method, and the spatial distribution of As, Cr(Ⅵ) and NO₃^--N were obtained by GIS. The human health risk of the groundwater contaminants were assessed by using human health risk assessment model. The results show that the concentration of As, Cr(Ⅵ) and NO₃^--N of groundwater in the study area exceeds the limits, the carcinogenic risk of As for adults reaches 3.50×10^-4, beyond the limit of 1.00×10^-4. A long-term exposure to As increases the risk of getting cancer. The ranking of non-carcinogenic risk of As, Cr(Ⅵ) and NO₃^--N is Cr(Ⅵ) > NO₃^--N > As,the non-carcinogenic risk of Cr(Ⅵ) for children reaches 8.693 7, far beyond the limit of 1.000 0. The human health risks resulted from oral exposure to the three contaminants are higher than those from dermal exposure. Spatially, As carcinogenic risk area is up to 42.82%, and the area ratios of the non-carcinogenic risk caused by As, Cr(Ⅵ) and NO₃^--N are 69.19%、69.06% and 66.55% respectively, the local water safety is a serious problem.

In order to provide a theoretical basis for the treatment design of a carbon tetrachloride(CT) contaminated site in the northern China, based on the sampling work and the geochemical reductive dechlorination process, we selected sulfate, ferrous iron, chloridion, trichloromethane, and bicarbonate as the target components, and compared the differences of the mass concentration between the selected components in the central and the outer part of the CT plume to analyze the geochemical characteristics of natural restoration of the site. The results show that there is a clear spatial correlation among the aforementioned components in the central part of the pollution plume. That is, the mass concentration of the reactant sulfate decreased obviously with the significant increases of the proportion of the product's divalent iron and the concentration of the degradation product chloride ion and chloroform correspondingly. Chloridion and trichloromethane, as dechlorination products, rise considerably with the decrease of bicarbonate. The relationship described above indicates the occurrence of the degradation of CT. The analysis of geochemical characteristics demonstrates that the site has an appreciable natural attenuation potential.

In this study, we applied both cross-correlation coefficient from fitting residual and depth weight to the constrained model of regularization gravity inversion to improve the reliability. In our approach, for the solutions in the system linear equations of gravity 3D inversion, damping LSQR algorithm method was introduced. Combined with the equivalent geometric trellis technology, the large matrix was divided into several sub-matrixes for storage and computation according to the model unit. The results of the theoretical model indicate that through the application of the cross-correlation coefficient with the depth weight into the constraint inversion model at the same time, the true anomaly can be clearly reflected. The damping LSQR algorithm method is sufficient for improving thousands or even tens of thousands of times of storage, and for increasing several times of computation rate. Thus, a large scale inversion calculation can be realized on a normal computer. The developed model is applied to the buried granite positioning in Luziyuan area, and the result is consistent with the true situation.

In order to overcome the shortcomings of using ships to measure sea-depth with low efficiency and high cost, the authors selected the Mariana Trench area formed by the Western Pacific plate dive to the Philippine plate as the experimental area, and used gravity anomalies data to inverse the sea-depth according to the gravity-geologic method. The density difference constant of the GGM (gravity-geologic method) model was determined to be by using the remove-restore technique. The differences between the GGM sea depth model, the ETOPO1 model and the model 1 which directly gridded dispersed ship data were analyzed and compared, and the landforms of the "challenger abyss" trench were studied based on the inversion results. The result shows that the seafloor topography computed by GGM model is superior to that by the ETOPO1 model, and even better than the results of the directly gridding of the ship survey data. The relative error of the model is not related to sea depth, but affected obviously by the change of seafloor topography. The sea-depth differences between the models are large in the area where the ship data are missing or too sparse. The landforms on the both sides of the "challenger abyss" trench are different. In the south side, when the water depth is less than 5 000 m, the gentle slope is about 2°-5°; while the water depth is greater than 5 000 m, the slope is increased significantly to about 10°-15°. In the north side, the slope is about 10°-15°. There is a buffer zone near latitude.

Located in the southwestern part of the East China Sea continental shelf basin, the Lishui-Jiaojiang sag is a Cenozoic fault depression with typical east fault and west overpassing characteristics developed on the basis of the Mesozoic residual basins,and it is a new area for oil and gas exploration. Due to the complex geological conditions in this area such as the superimposed structure and the sedimentary thickness, the useful reflection data are not available through seismic exploration. The authors adopted the combination of gravity and magnetic data that are used for a wide area and large depth with seismic data to describe the structure, igneous rock,and lithological characteristics of the basement, and divided the regional faults by using the step boundary recognition technology of gravity and magnetic data. The inner faults in the sag show a north-eastward distribution, which control the shape of the sag. The fault depression is characterized by many small secondary depressions formed by the faults. The Mesozoic and Cenozoic igneous rocks have high gravity and magnetic anomalies. We obtained the strati-graphic, igneous and lithology distribution characteristics from the seismic profile with good quality,and established the formula for the calculation of the mulch-continuous domain strata. The Mesozoic strata are relatively developed in the region, and there are less Mesozoic and cenozoic igneous rocks in the sag, which will not cause the great damages to oil and gas structure. Therefore, this sag has a good oil and prospects.

Jiayu fault has been confirmed as a concealed fault, which is located in the northeast of Jiayu county. The fault is about 40 kilometers long. It stretches nearly EW-NEE, traverses the Yangtze River from the southwest of Honghu Laowan, passing the northern edge of Maan Mountain, and extends eastward to the Futou Lake. Although the eastern end of the fault is clearly exposed, the tail of the fault is not apparent. The lack of small scale geophysical data in the area leads to the lack of relevant evidence for the trend and activity of the fault. In this study, shallow seismic wave combined with refraction tomography was used to receive artificial seismic wave at 2 meters interval. Through the use of multiple coverage technique and dense spot collection refraction records, the data were separately reflected and tomographically imaged, and then the shallow seismic reflection profiles and high-resolution refractive tomography profiles were obtained, and the data is interpreted by referring to the relevant regional seismic safety evaluation drilling data.. The comprehensive research results show that the application of shallow seismic reflection and high resolution refraction can be complementary, especially in the area where the external interference is serious, as the high-resolution seismic refraction tomography can reduce the chances of misjudgment of shallow seismic reflection. In addition, the study confirmed the specific location and its normal fault characteristics of Jiayu fault, which is characterized by the decline of the northern plate and the rise of the south plate, and the fault cut through the Quaternary sedimentary layer.

AVO (amplitude versus offset) is a technique for studying lithology and detecting hydrocarbon seismic exploration by using amplitude information. Conventional single interface reflection coefficient can be calculated by Zoeppritz equation; however, the reflection characteristics of layered media seismic wave is not only related to incident angle, but also differences of physical property, incident wave frequency, formation thickness, thin interbedded structure, the formation non-uniformity and other factors, and all the factors related tuning effects are fully considered in the theory of propagation matrix. Based on the data calculation of high-precision synthetic seismogram in heterogeneous underground media, we compared the simulation results of Zoeppritz equation, Shuey two-term approximation equation, Shuey three-term approximate equation, and propagation matrix algorithm. The study shows that at a small incident angle, the reflection amplitude and waveforms of Zoeppritz equation, Shuey two-terms, and Shuey three-term approximation are basically the same; while at a large incident angle, those of Zoeppritz equation and Shuey three-term approximation are closer. Under the condition of small incident angles and shallow layers, the seismic responses of Zoeppritz equation and propagation matrix algorithm is almost the same, but different at large incident angles and deep layers. It is illustrated that the tuning effects and multiple wave interferences cannot be ignored.

The Yitong basin is a Cenozoic fault basin in the northern part of the Tan-Lu fault zone. The development and evolution of the Yitong basin is accompanied by strong volcanic activity. The distribution of buried volcanic edifices is of great significance to the study of volcanic evolution, geothermal exploration, and development in Yitong basin. In this study, we took the Hengtoushan volcano in the Yitong volcanic group as the research object, and used aeromagnetic measurements to determine the plane range of the buried volcanic edifice. The magnetic anomaly of the Hengtoushan volcanic area ranges of 2.6 km². Using an electromagnetic sounding (MT) section through the Hengtoushan volcanic area, we obtained the deep electrical structure, and analyzed the cause of the Hengtoushan volcano. The study shows that the volcanic strata formed in the first part of the Quaternary in Early Pleistocene, and under the action of torsional stress the basaltic magma crushed out of the surface along the Maanshan fault or stuck in the fault. Now, the magma channel is closed. Using the controllable source audio magneto telluric sounding method, the fine electrical structure near the Hengtoushan volcano was obtained to determine the shape and distribution range of the concealed magma capsule. Based on the above results, we obtained a clear understanding of the formation time, deep dynamic process, the spatial morphology, and the tectonic environment of the Hengtoushan volcano. We established a geophysical imaging mechanism for a buried volcanic edifice, which provides a reference for the development of volcanic geothermal systems in the Yitong basin.

Water resources and hydropower projects often involve rock mass foundation and rock slope. Weathering and unloading can lead to rock disintegration. The impact on construction work is remarkable. The P-wave velocity of rock mass and the rebound value of rock are measured along the exploratory waist line, and then they are clustered and analyzed respectively,vand further are divided into different data groups. According to the different essential characteristics of weathering and unloading,vits P-wave velocity has gradient difference, no matter it is weathered or unloaded; however, the rebound value has a gradient difference only in weathered rock mass, but not in unloaded rock mass. Using the mathematical model of Boltzmann function,vthe authors analyzed the longitudinal wave velocity and rebound value by fitting calculation, made a numerical discrimination on weathering and unloading of rock mass, and further quantitatively divided the weathering zone and unloading zone, and determine their boundaries. The application results show that the numerical discrimination method is easy to operate,vcan scientifically and objectively distinguish the weathering and unloading,vcan accurately determine the boundaries of the weathering belt or the unloading zone,vand can solve engineering geology problems quantitatively.

The toppling deformation is common in the downstream slopes of Yuqu River in Tibet, and the deformation characteristics are typical in the southeast "three river area" of the Qinghai-Tibet plateau. As the development of hydro projects in this region, the slope toppling deformation is becoming more and more prominent. The correlation of the deformation characteristics of slopes and slates which compose the slopes was mainly studied through field investigation, exploration and field test. Then three types of toppling were analyzed:1) the toppling-broken mode is brittle failure, and the feature is mainly progressive backward failure from the front to the rear, which is suitable for stability analysis by limit equilibrium method; 2) the toppling-bending mode is ductile deformation, and the failure mode is mainly the collapse and relaxation of the shallow part of the slope, which is suitable for the stress analysis based on a discontinuous medium model; 3) the toppling of crumpled mode is similar to the toppling-bending type, which only occurs when the glacier is superimposed on the basis of the toppling-bending.

A geological disaster induced by reservoir impoundment is common. It is important to study the characteristics and stability of deposit slope at reservoir bank before and after impoundment for prevention of such a disaster. Based on the in-situ detailed engineering geological investigation and monitoring materials, the structural and deformation characteristics of deposit slope were analyzed, and the formation and deformation mechanisms were discussed in this study. Finally, based on the discrete element method, the stability of this slope was evaluated. Based on the above research results, the deposit slope was formed from the ancient slide, and the reservoir water level raised by nearly 40m in two months, thus activating the ancient landslides and resulting in the deformation. The engineering treatment such as drainage tunnels and drainage holes slow down the deformation of the slope dramatically, and the deformation of some observation points has a convergence trend.

In a construction of airport, highway, railway, mine and other large-scale infrastructure construction projects, a vertical fill support structure become an indispensable part with the urbanization of a loess area. However, the slope supporting structure in loess area is prone to pile foundation settlement, pile bending,and pile plate wall cracking. In order to analyze its deformation characteristics, an all-weather continuous monitoring was carried out by using IBIS-L. The point and surface data collected show the followings:1) the deformation of supporting structure showed obvious regional differences in general, the maximum deformation value of the last 15 days was 26.6 mm; 2) the displacement of object monitoring points increased in a "wavy" shape at intervals of 24 hours with no convergence trend, which may cause the overall instability of the slope; 3) taking Pix8 as an example, combined with a temperature monitoring, the theoretical calculation results agreed with the monitoring data, which revealed the reason why the s-t curve increased in wave shape. It is concluded that the deformation of mass concrete in an atmospheric temperature field has the characteristic of "lag effect".

The most load of the arc dam is transmitted to the abutment rock mass of both sides through the arch dam foundation. How to accurately evaluate the quality of dam foundation rock mass during construction period is important for engineering geology research of arch dam foundation rock mass. Based on the engineering geological conditions, the authors studied the engineering geological characteristics of foundation rock mass, such as lithology and rock mass structure etc., and built the rock mass quality classification standard, combining with the field and laboratory tests and the sonic test of rock mass. According to the rock mass quality classification during excavation, most of the rock mass is of gradeⅡ, a small amount of grade Ⅲ₁, and very small amount of Ⅲ₂, which are agreed with the result of the feasibility study stage. The quality of rock mass meets the requirement of dam construction. The distribution of rock mass is continuous and beneficial to the arch dam.

Stability of surrounding rock mass of a cavern in a fractured rock mass is an important engineering geological problem to be solved in an underground plant of a pumped storage power station. Taking a pumped storage power station as an example, in order to accurately predict the unstable block position before excavation, we statistically analyzed the fractures in the hole, and determined the law of fracture development with combination of the fault development in the plant area. On the basis, the rock mass was divided into five tectonic zones:A, B, C, D and E. By the Unwedge program, the position of the potential block was determined and its stability was evaluated. The results show that the fractures are controlled by multi-stage tectonic faults, and are directional in a certain range. The occurrence of the dominant fractures in region A, E are close to the tectonic fault occurrences, and the dominant fractures in region B, C, D are cross the tectonic faults obliquely; six potential unstable blocks are formed on each side of the upper and lower side walls of the plant, ten potential unstable blocks at the top of the arch, and one potential unstable block at the right end wall.

Grouting works are underground concealed works, and their geological conditions and different rock properties constrain the actual site construction technology, and influence the optimal design of dam anti-seepage curtain. The lack of analysis of geological conditions will bring a lot of uncertainty to the grouting engineering. Prediction of geological condition is well studied presently in tunnel excavation, but not the geological factors in grouting engineering. Based on the example of dam anti-seepage grouting curtain at the Wudongde hydropower station, the authors analyzed and studied the geological factors such as karst, breccia, fault, large structural plane, and the large intersection angle between the curtain and terrane strike. According to the characteristics of different geological factors, the authors put forward a series of treatment measures such as thick slurry backfilling, deepening and encryption of grouting hole, dynamic adjustment of grouting pressure and material. The study can reduce cognitive blindness of geological conditions, and provide necessary support for curtain grouting optimization.

In a step by step excavation engineering such as high slope,large underground cavern and deep foundation pit, the project image changes greatly, the excavation duration is long, the position of excavation face is constantly changing, and the geological information of excavation face needs to be collected in time. These characteristics are not conducive to build a 3D image model. These problems cannot be solved by using the traditional static method. Taking the dam foundation surface slope of Wudongde hydropower station as a typical example of step by step excavation engineering, the authors explored a 3D image modelling method. Based on the oblique photographic data with unmanned aerial vehicle (UAV), image control point's measurement, and data processing and modelling, the overall 3D images are obtained. The quality of the 3D images is good and the coordinate error is generally 5.1-7.9 cm, and the coordinate precision meets the engineering requirement. This 3D image model construction method lays a foundation for engineering information storage, analysis, display and later use.

Considering the difficulty of the traditional method in the classification and evaluation of surrounding rock stability of TBM tunnel, a new system of stability classification of the surrounding rock with shield TBM tunnel is developed. Based on the characters of a shield TBM construction and some regular classification methods, the evaluation factors were selected, including rock rebound value, cutterhead thrust, cutterhead torque, content of rock chips cut by TBM, groundwater flow and angle between the maximum principal stress and the tunnel axis. The multi-factor model of a stability analysis of surrounding rock was established by using fuzzy comprehensive evaluation method. The surrounding rock stability was quantitatively assessed by determining weight vector of impact factors and by selecting membership functions. This method was applied to the stability evaluation of tunnel surrounding rocks during a double shield TBM construction. The results showed that the tunnel sections of No. 1, 2, 3 and 4 were relatively stable, relatively stable, local stabile, and instable respectively. Their maximum membership degrees were 0.494, 0.403, 0.388, and 0.442, corresponding to the surrounding rocks of Ⅱ, Ⅱ, Ⅲ and Ⅳ. The developed method based on fuzzy comprehensive evaluation is reasonable, and the evaluation result is reliable. The research results have reference value for surrounding rock stability evaluation, surrounding rock classification, and support mode selection of shield TBM construction.

The compaction rate of gravel soil is usually characterized by the "relative density", which is used to evaluate the compaction quality of dam construction. Restricted by the size and energy limitation of the laboratory test equipment, the laboratory tests are difficult to reflect the actual situation of high strength compaction of gravel soil by large rolling equipment;and the maximum dry density of the gravel soils obtained in laboratory tests is often much lower than the actual one, so it cannot be directly used in practical engineering. To the sand and gravel materials for the Dashixia high concrete faced rock-fill dam, the field large-scale relative density test of original gravel soil was carried out by using the actual rolling equipment and large relative density bucket on the site, the compaction characteristics of soil was studied, and further the relative density characteristic indexes of soils with different gradation (coarse grain content) were determined. The test results show that the maximum dry density of gravel soil determined by field test is greatly improved compared to a general laboratory test; the minimum and maximum dry densities of gravel soil show a tendency of increasing at first and then decreasing with the increase of the coarse grain content, and there is an optimal coarse grain content value with the highest compaction density of soil; the strong vibration compaction results in different degrees of particle crushing effect on weakly cemented gravel materials, and the degree of particle crushing is related to the original grading characteristics of soil materials.