三维注浆模型试验系统研制及应用

Development of a 3D grouting model test system and its application

为研究注浆扩散规律和加固机制,研制了三维注浆模型试验系统,该系统由承载试验台、伺服稳压供水单元、注浆单元、多元信息监测单元及图像采集单元组成。该系统主要功能包括不同岩体介质中参数灵活可调的多孔注浆、多序次注浆模拟试验及被注岩体内部物理场信息实时采集,其主要优势体现在:(1)试验腔设计为组合桶式结构,密封性强,拆卸方便,利于注浆加固体细部研究;(2)多腔气动联合控制水压加载方式可提供持续稳压的地下水环境;(3)多元信息并行实时监测系统可同时采集被注岩体内不同空间位置的总压力、孔隙水压力及位移等信息,实现注浆过程中物理参量时空变化规律的研究。利用该试验系统进行黏土介质单孔注浆和多孔分序次注浆模拟试验,获得注浆压力p变化特征及土体内部力学响应规律:p-t曲线呈多个波峰-波谷旋回,表征劈裂注浆为主的加固模式;注浆荷载作用下,总压力、孔隙水压力、有效应力与注浆压力基本同步变化,注浆结束点达到峰值,其后开始衰减并逐渐趋于稳定;与单孔注浆相比,多孔、多序次注浆可显著提高土体有效应力,黏土逐渐压缩固结,力学性质改善。试验表明,黏土介质以劈裂注浆为主,不同序次浆脉间接触关系复杂,可划分为剪切劈裂、原位顺层劈裂及入侵劈裂3种基本模式;采用多孔、小注浆速率试验方法,可减小围岩扰动,增大注浆量及土体压缩固结程度,提高注浆加固效果。研究成果对揭示黏土介质注浆机制具有一定的科学价值。

A 3D grouting model test system, which consists of bearing test rig, servo voltage supply unit, grouting unit, multivariate information monitoring unit and image acquiring unit, is developed to investigate the grouting diffusion process and reinforcement mechanism. The main functions of this system are the lacunose, multiple sequence and parameter flexible model test of the grouting and the real-time collection of the physics field information during the grouting. The major advantages of the system include：（1） The test cavity is designed as composite barrel structured, strong leak tightness and convenient disassembly, in favor of studying grouting solid details;（2） the loading method of multi-cavity control hydraulic pneumatic joint can provide continuous steady pressure groundwater environment;（3） a multi information parallel real-time monitoring system can collect the information of the total pressure, pore water pressure and displacement of different spatial positions in the injected rock body, and realize the spatial and temporal variation of physical parameters in the grouting process. The testing system is used to perform the simulation tests of single hole grouting and grouting in a single hole, and the variation of grouting pressure P and the mechanical response of soil are obtained. The p- t curve shows multiple peak- trough cycle and characterizes strengthening mode of splitting grouting. The total pressure, pore water pressure, effective stress and grouting pressure change almost synchronously under the grouting loading; reach the peak values at the end point of grouting, and then begin to attenuate and gradually to be stabilized. Compared with single-hole grouting method, the multi-hole grouting method can improve the effective stress of soil dramatically. It is demonstrated that fracturing grouting is the main clay medium. The contact relationship between different orders of slurry veins is complex, and can be divided into 3 basic modes： shear splitting, in situ splitting and intrusion splitting. The test method of porous and small grouting rate can reduce the disturbance of surrounding rock, increase the amount of grouting and the degree of consolidation of soil, and improve the effect of grouting reinforcement.