悬索桥隧道式锚碇与围岩系统的破坏模式研究

The anchorages are unparalleled structures only in a suspension bridge, and as main bearing facilities, play an important role in connecting the superstructures and the ground. The tunnel anchorage, as one alternative type of the anchorages, has more advantages over its counterpart, the gravity anchorage. With the tunnel anchorages adopted, not only can surface excavation be reduced to protect the environment, and natural condition of the rock be utilized and potential bearing capacity of surrounding rock be mobilized to save engineering cost, but also the technological predominance of auxiliary engineering measures, such as prestressed concrete, anchoring piles, rock anchors and collar beam between the two separated anchorages, can be easily cooperated to work together harmoniously under the circumstances of poor rock quality. There are plentiful high mountains and deep canyons in west part of China, and long-span bridge construction is inevitably encountered in order to realize leapfrogging development of the transportation infrastructure. Western mountainous areas usually possess the conditions for constructing tunnel anchorages, and therefore, the tunnel anchorages, which are conformed to the conception of resource conservative and sustainable society, extremely have application and popularization value in western underdeveloped region. The scientific and technological problem about the design, construction and operation of tunnel anchorages should be further investigated. Combining the engineering of western tunnel anchorages for the Balinghe Suspension Bridge, this paper probed into the survey method and in-situ test method for tunnel anchorages, scientific rock quality evaluation of surrounding rock to provide reasonable physical and mechanical parameters for design, construction and operation of tunnel anchorages, bearing capacity estimation for tunnel anchorage, deformation prediction of the anchorage-rockmass system, tunnel-anchorage slope stability analysis and the evaluation of excavation stability and degree of safety of the anchorage tunnel. The following outcomes were obtained: 1. Materials of tunnel anchorages of suspension bridge built (and in progress) at home and abroad were systematically sorted out, with the engineering geological condition and geomechanical property of surrounding rock around the anchorage tunnel, the design size of anchorages and the construction method of anchorage tunnel paid more emphasis on, to unveil the internal relationship between the engineering geological conditions of surrounding rock and the design size and axis angle of anchorages and provide references for future design, construction and study of tunnel anchorages. 2. Physical and mechanical parameters were recommended based on three domestic and foreign methods of rock quality evaluation. 3. In-situ tests, adopting the back-thrust method, of two kinds of reduced scale model, 1/30 and 1/20, for the tunnel anchorages were conducted in the declining exploration drift with rock mass at the test depth being the same as surrounding rock around real anchorages, and reliable field rockmass displacement data were acquired. Attenuation relation between the increment of distance from the anchorage and the decrement of rockmass displacement under maximum test load, and influential scope suffered by anchorage load were obtained. 4. Using similarity theory, the magnitude of real anchorage and rockmass displacement under design load and degree of safety of the anchorage system were deduced. Furthermore, inversion analysis to deformation modulus of slightly weathered dolomite rock, the surrounding rock of anchorage tunnel, was performed by the means of numerical simulation. 5. The influential law of the geometrical size to the limit bearing capacity of tunnel anchorage was studied. 6. Based on engineering geological survey data, accounting for the combination of strata layer and adverse discontinuities, the failure patterns of tunnel anchorage slope were divided into three modes: sliding of splay saddle pier slope, superficial-layer slippage, and deep-layer slippage. Using virtual work principle and taking anchorage load in account, the stability of the three kinds of failure patterns were analyzed in detail. 7. The step-by-step excavation of anchorage tunnel, the numerical overload and the staged decrement of rock strength parameters were numerically simulated to evaluate the excavation stability of surrounding rock around anchorage tunnel, the overload performance of tunnel anchorage, and the safety margin of strength parameters of the surrounding rock.

地下水流动数值模拟的并行计算方法研究

Numerical modeling of groundwater is very important for understanding groundwater flow and solving hydrogeological problem. Today, groundwater studies require massive model cells and high calculation accuracy, which are beyond single-CPU computer’s capabilities. With the development of high performance parallel computing technologies, application of parallel computing method on numerical modeling of groundwater flow becomes necessary and important. Using parallel computing can improve the ability to resolve various hydro-geological and environmental problems. In this study, parallel computing method on two main types of modern parallel computer architecture, shared memory parallel systems and distributed shared memory parallel systems, are discussed. OpenMP and MPI (PETSc) are both used to parallelize the most widely used groundwater simulator, MODFLOW. Two parallel solvers, P-PCG and P-MODFLOW, were developed for MODFLOW. The parallelized MODFLOW was used to simulate regional groundwater flow in Beishan, Gansu Province, which is a potential high-level radioactive waste geological disposal area in China. 1. The OpenMP programming paradigm was used to parallelize the PCG (preconditioned conjugate-gradient method) solver, which is one of the main solver for MODFLOW. The parallel PCG solver, P-PCG, is verified using an 8-processor computer. Both the impact of compilers and different model domain sizes were considered in the numerical experiments. The largest test model has 1000 columns, 1000 rows and 1000 layers. Based on the timing results, execution times using the P-PCG solver are typically about 1.40 to 5.31 times faster than those using the serial one. In addition, the simulation results are the exact same as the original PCG solver, because the majority of serial codes were not changed. It is worth noting that this parallelizing approach reduces cost in terms of software maintenance because only a single source PCG solver code needs to be maintained in the MODFLOW source tree. 2. P-MODFLOW, a domain decomposition–based model implemented in a parallel computing environment is developed, which allows efficient simulation of a regional-scale groundwater flow. The basic approach partitions a large model domain into any number of sub-domains. Parallel processors are used to solve the model equations within each sub-domain. The use of domain decomposition method to achieve the MODFLOW program distributed shared memory parallel computing system will process the application of MODFLOW be extended to the fleet of the most popular systems, so that a large-scale simulation could take full advantage of hundreds or even thousands parallel processors. P-MODFLOW has a good parallel performance, with the maximum speedup of 18.32 (14 processors). Super linear speedups have been achieved in the parallel tests, indicating the efficiency and scalability of the code. Parallel program design, load balancing and full use of the PETSc were considered to achieve a highly efficient parallel program. 3. The characterization of regional ground water flow system is very important for high-level radioactive waste geological disposal. The Beishan area, located in northwestern Gansu Province, China, is selected as a potential site for disposal repository. The area includes about 80000 km2 and has complicated hydrogeological conditions, which greatly increase the computational effort of regional ground water flow models. In order to reduce computing time, parallel computing scheme was applied to regional ground water flow modeling. Models with over 10 million cells were used to simulate how the faults and different recharge conditions impact regional ground water flow pattern. The results of this study provide regional ground water flow information for the site characterization of the potential high-level radioactive waste disposal.

成矿流体构造动力学研究—以冀西北后沟金矿和山东七宝山金矿为例

Tectonic dynamics of metallogenetic fluids is a new crossed subjects among fluid geology, mineral deposit geology and structural geology, and is one of the major current projects of geosciences. It is mainly focused on structures and tectonic dynamic induced by fluid motion, variation of physical condition of fluids (such as temperature and pressure), and interaction between chemical component of fluids and wall rocks in the crust. It takes features of deformation and metamorphysim, which formed during interaction between fluids and rocks and have been perserved in rocks, as basic research objects. After studying types, orders, distributions and fabrics of these features, and analyzing and testing physical and chemical information from these features by some techniques, it is intended to reconstruct moving process of fluids, dynamics of interaction between fluids and rocks, and dynamics of mineralizations. Three problems of tectonic dynamics of metallogenetic fluids, which have not been paid much attentions before, have been studied and discussed in this report. Three relative topics are including: 1)Double-fracturing induced by thermal stress and pressure of fluids and mineralization of Gold-copper in Breccia Pipe at the Qibaoshan in Shandong Province; 2)Parting structures induced by K-metasomatism in the Hougou area, northwestern Heibei province; 3)Migration mechanism of dissolved mass in Fe&S-rich fluids in Hougou gold deposit in Heibei province. After a synthetical study of two years, the author has made some new processes and progresses. The main new advances can be summaried as the following: 1)Thermal stress of fluids formed by temperature difference between fluids and country rock, during upword migration process of fluids with high temperature and pressure, can make rock to break, and some new fractures, which surfaces were uasally dry, formed. The breccia pipe at the Qibaoshan area in Shandong province has some distinct texture of fluidogenous tectonics, the breccia pipe is caused by double-fracturing induced by thermal stress and pressure, distribution of gold-corpper ore bodies are controlled powerfully by fluidogenous tectonics in the breccia pipe. 2)The author discovered a new kind of parting structures in K-alterated rocks in the northwestern part of Hebei province. The parting structures have some distinct geometry and fabrics, it is originated from the acting and reacting fores caused by K-metasomatism. Namely, the crystallizations of metasomatic K-feldspars are a volume expansion process, it would compress the relict fluid bodies, and the pressures in the relict fluid bodies gathered and increased, when the increased pressure of the fluid relict bodies is bigger than the strength of K-feldspars, the K-feldspars were broken with the strong compression, and the parting structures formed. 3)Space position replacing is a important transport pattern of dissolved mass in Fe&S-rich fluid. In addition, basing on views of tectonic dynamics of metallogenic fluids, and time-space texture of fluid-tectonic-lithogenetic-mineralization of the known gold-corpper mineral deposit and the subvolcanic complex at Qibaoshan area in Shandong province, this report does a detail prodict of position-shape-size of two concealed ore-bearing breccia pipe.