一种兼具渗透与劈裂功能的复合注浆材料研发与现场试验

Experimental and applied research on a composite grouting material with the functions of permeable and splitting

碎粉岩富水地层具有结构松散、粒径较小、黏聚力低、自稳性差等特点,传统浆液难以有效渗透加固。以碎粉岩工程地质特征为导向,利用有机-无机材料复合协同效应研发一种集渗透胶结及劈裂加固于一体的新型注浆材料(PSCG),克服碎粉岩“吃水不吃浆”这一工程难题。首先通过室内力学试验与注浆模拟试验验证上述材料研发思路的可行性,并选取碎粉岩加固所需关键指标进行物理力学性能测试(凝结时间、持水率、加固体抗渗性、强度、体积收缩率),结合微观测试手段(SEM、FTIR)揭示新材料的注浆加固机制,最后通过现场试验,研究PSCG材料对碎粉岩地质的加固效果。研究结果表明:PSCG材料具有渗透-劈裂双重作用同步加固效果。一方面,丙烯酸钠聚合生成网络状高分子结构,与水泥水化产物、水泥颗粒相互贯穿形成具有抗分散效果的三维互穿空间结构,并且有机-无机材料接触界面被改良,裂缝被充填,加固体7 d强度可达27.01 MPa。另一方面,丙烯酸钠溶液在注浆压力及毛细作用作用下渗入碎粉岩颗粒孔隙间并发生聚合反应,将碎粉岩颗粒锁合成整体结构,同时,碎粉岩中的金属与凝胶中羧酸基团形成强烈的配位作用,增加了聚合物网络的交联密度,提高了凝胶的力学性能,渗透区加固体7 d的强度可达2.4 MPa,渗透系数高达5.9×10^(-7)cm/s。结合现场试验结果,PSCG材料对碎粉岩地层具有堵水、加固双重效果。

In view of the problem of water and mud inrush when the#5 construction branch tunnel of Xianglu Mountain in Central Yunnan passes through the fragmented powder rock,guided by the engineering geological characteristics of fragmented powder rock as the,and proposes for the first time to develop a new type of grouting material(PSCG)that integrates infiltration cementation and splitting reinforcement through organic-inorganic material composite to realize multi-mode reinforcement of fragmented powder rock stratum.By compounding sodium acrylate solution with sulphoaluminate cement,making full use of the percolation characteristics of fragmented powder rock stratum,under the grouting pressure,the sodium acrylate solution diffuses into the pores of fragmented powder rock particles with its high permeability characteristics,and the sulphoaluminate cement forms a splitting slurry vein in the fragmented powder rock stratum.The synergistic effect of organic-inorganic materials is used to overcome the engineering problem of"water can penetrate,but slurry cannot penetrate"of fragmented powder rock.In this paper,the feasibility of the above material development idea was verified through laboratory mechanical test and grouting simulation experiment,and the key indicators required for the reinforcement of fragmented powder rock were selected for physical and mechanical properties test(setting time,water holding rate,impermeability of stone body,strength and volume shrinkage),and the grouting reinforcement mechanism of the new material was revealed by microscopic testing methods(SEM and FTIR).Finally,the reinforcement effect of PSCG on fragmented powder rock geology was studied by field test.The results show that the PSCG material has the simultaneous reinforcement effect of the combined infiltration and splitting mode.There are organic-inorganic composite effect,micro-crack filling effect and hydrodynamic anti-dispersion effect in the stone body in the splitting zone,that is,sodium acrylate polymerization generates network polymer structure,which penetrates with cement hydration products and cement particles to form three-dimensional interpenetrating spatial structure with antidispersion effect.In addition,the contact interface between organic-inorganic materials is improved and cracks are filled.The strength of the stone body can reach 27.01 MPa at 7 days.There are capillary adsorption,chemical bond and physical lock cooperation in the stone body of the infiltration zone,that is,the sodium acrylate solution penetrates into the pores of the fragmented powder rock particles under the action of grouting pressure and capillary action and undergoes polymerization reaction,and the fragmented powder rock particles are locked into the overall structure.At the same time,the metal in the fragmented powder rock and the carboxylic acid group in the gel form a strong coordination effect,which increases the crosslinking density of the polymer network and improves the mechanical properties of the gel.The strength of the stone body in the infiltration zone can reach 2.4 MPa in 7 days,and the permeability coefficient is as high as 5.9×10^(-7)cm/s.Combined with the field test results,PSCG material has the dual effects of water plugging and reinforcement on the fragmented powder rock stratum.