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永久船闸是三峡工程的重要组成部分,其高边坡是在花岗岩山体中开挖而成的,最大开挖深度达170m。由于开挖卸载,在岩体中形成卸荷应力场,这种新的应力场往往成为岩体持续变形的主要因素,而岩体的持续变形可对工程建筑物(特别是高边坡)的稳定性产生致命的影响。另外,岩体内的地应力释放,使岩体产生回弹变形,岩体结构松弛破裂,岩体力学性质恶化。因此,在永久船闸的开挖过程中,对其进行地应力测量和监测,不仅对边坡整体稳定性分析和安全预报具有重要意义,而且还为制定合理的施工方案,并对边坡的加固处理提供依据。按设计技术要求,地应力测量及其变化监测在永久船闸北坡第四层排水洞内进行,地应力测量和监测的布置如图1所示。按照要求,首先在NB4—7测孔中进行5个测段的绝
The permanent ship lock is an important part of the Three Gorges Project. Its high slope is excavated in granite hills with a maximum excavation depth of 170m. As a result of excavation and unloading, the unloading stress field is formed in the rock mass. Such new stress field often becomes the main factor for the continuous deformation of the rock mass, and the continuous deformation of the rock mass can affect the deformation of the engineering structures (especially the high slope) Stability has a fatal effect. In addition, the release of geostress in the rock mass causes the rock mass to rebound and deform, the rock mass structure relaxes and cracks, and the mechanical properties of the rock mass deteriorate. Therefore, during the excavation of a permanent ship lock, the measurement and monitoring of the geostress of the ship are not only significant to the overall stability analysis and safety prediction of the slope, but also for the formulation of reasonable construction plans and reinforcement of the slope Processing provided basis. According to the design technical requirements, the measurement of ground stress and its change monitoring are carried out in the drainage tunnel on the fourth floor of the north slope of the permanent ship lock. The measurement and monitoring of ground stress are arranged as shown in Figure 1. In accordance with the requirements, first of all, in the NB4-7 hole measured five absolutes