软基岩层上的混凝土重力坝设计及基础处理

坝体结构稳定和坝基防渗是决定工程安全和预期效益的关键因素。柏岭寺水库水利枢纽工程设计方案,大坝采用碾压混凝土重力坝,大坝基础开挖后,坝基持力层由砾岩变为砂岩。现有的混凝土重力坝大多数建在硬岩,软基上建坝的较少,通过调整坝体边坡,改变局部尺寸和坝基灌浆方案的措施,解决了软弱基岩上坝体稳定,坝基渗漏等问题,可为类似工程设计方案的选定提供一定的参考价值。

针对软土地层基岩凸起大直径盾构刀盘选型分析

随着TBM和盾构设备在铁路、地铁、电力、水利、城市交通等施工领域的运用,隧道工程已向长距离、超埋深、高水压、大直径等方面发展,同时也增加盾构施工难度,对设备的系统配置要求越来越高。特别在大型城市市区内施工,建筑物密集、隧道埋深浅、周边环境复杂,更加大了工程施工风险和施工难度。确保工程安全快速施工,前期在设备选型配置阶段进行设计及分析至关重要。本文以某道路改造工程为依托,从地质详勘分析、复合刀盘设计、刀具选择、类似工程施工参考进行分析,实现盾构在上软下硬、基岩凸起段地层中的长距离安全快速掘进,为区间的盾构设计、盾构施工提供依据。

Control over Surrounding Rocks Deformation of Soft Floor and Whole-Coal Gateways with Trapezoidal Supports

In Gengcun Colliery, Yima Coal Group Co. Ltd.the characteristics of the gateways of thick coal seam and the coal seam is with fully mechanized sublevel caving mining are that the thickness of roof coal seam of gateways is larger, their surrounding rocks are the whole-coal mass and the coal seam is prone to Spontaneous Combustion. With the natural equilibrium arch theory, the reasonable adjacent distance of No.11 mine-type metal supports was calculated in trapezoidal gateways based on these characteristics. Then, in-situ supporting experiments were carried out. The results indicate that under the action of virgin rock stress, the width of broken rocks zone of surrounding rocks is 1.7–2.0 m in return heading and 1.1–1.3 m in going headway. And their surrounding rocks belong to the Ⅳ-type soften rock and the Ⅲ-type common surrounding rock respectively. Therefore, under the movable abutment pressure, the gateways deformation is serious. It is suggested that the designed gateways have to use pre-broadened cross section to suit their deformation. At the same time, the accumulated water on gateway floor must be drained in time. These measures were taken in the 1302 and 1304 coal faces in Gengcun Colliery, and the satisfactory results have been obtained.

Unsaturated Creep Behaviors of Weak Intercalated Soils in Soft Rock of Badong Formation

The cutting slopes in soft rock of redbed appeared in Yichang-Badong highway often suffer from the instability along weak intercalations, so the creep behaviors of weak intercalated soils are crucially important for the stability of cutting slopes. Because the deformation of weak intercalated soils is significantly affected by water content due to the strong water sensitivity, it is necessary to study the influence of matric suction on the creep behaviors of weak intercalated soils. In order to find out the unsaturated creep characters of weak intercalated soils, a GDS unsaturated triaxial apparatus was used. Then the triaxial creep experiments on weak intercalated soil samples under varying matric suction were conducted to obtain the unsaturated creep curves. The results show that the weak intercalated soils have obvious creep behaviors, and the creep strain is in nonlinear relationship with stress and time. When the matric suction is constant, a larger deviator stress will lead to a larger creep strain; When the deviator stress is constant, a smaller matric suction will lead to a larger creep strain. Based on the Mesri creep model, an improved creep model for weak intercalated soils under varying matric suction was established, in which the relationship of stress-strain was expressed with a hyperbolic function, and the relationship of strain-time was expressed with power functions in stages. Then an unsaturated creep model including stress-matric suction-strain-time for weak intercalated soils was established based on the power function relationship between matric suction and Ed(a parameter of the improved creep model). The comparison of the calculated values of creep model and the experimental values shows that the creep behaviors of weak intercalated soils can be predicted by the unsaturated creep model by and large.