地质力学模型试验中软弱结构面内埋式位移系统的研制与应用

Design of structure inbuilt displacement measurement system in geomechanical model test and its application

在高拱坝坝肩稳定地质力学模型试验研究过程中,坝肩岩体内各软弱结构面的相对位移变化趋势是判定坝肩失稳及分析坝肩整体稳定安全度的重要参考依据。目前的量测仪器,如电阻应变片、表面位移计只能对坝体应变和坝肩抗力体表面位移进行量测,而对于坝肩岩体内软弱结构面的相对位移则难以获取。因此,针对上述问题,以电阻应变技术为基础,研制了用于获取结构面相对位移的内埋式位移系统,该系统由信号采集仪器、惠斯通电桥和位移传感器组成。在模型试验中,通过内埋式位移系统,获得加载过程中相应测点的应变变化过程,再由应变-位移关系曲线,即可得出位移值。结合锦屏一级高拱坝整体稳定地质力学模型试验,将该系统安装于需量测的坝肩软弱结构面上,获得了结构面在加载过程中的位移变化过程线,同时与大坝应变和坝肩表面位移监测成果进行对比分析,验证了内埋式位移系统的可行性,其测试成果可为判定坝与地基的整体稳定提供依据。

In high arch dam abutment stability geomechanical model test, the relative displacement of weak structural plane is the important reference to determine dam abutment instability and analyze whole dam abutment safety degree. But the current measuring instruments, such as resistance strain gage, surface displacement meter just can measure the strain of dam body and displacement of surface dam abutment;for the relative displacement of weak structural plane which in dam abutment is difficult to obtain. So in light of this problem, based on the resistance strain gage technology, a new type of inbuilt displacement system has been developed and installed on the structural planes to obtain the relative displacement of structure. This system are composed by signal acquisition instrument, Wheatstone bridge and displacement sensor. In model test, strain changing process is got using the inbuilt displacement system;and displacement value is got through the strain-displacement curve. In integral stability geomechanical model test of Jinping high arch dam, installing this system in weak structural plane, the relative displacement is obtained efficiently during the loading process. Comparing with the strain and the abutment surface displacement monitoring results, the feasibility of inbuilt displacement system is proved. The results can provide reliable data to determine the overall stability of the dam and foundation.