發(fā)布時(shí)間：2018-08-03 09:04

【摘要】：結(jié)構(gòu)面是廣泛分布于天然巖體中的不連續(xù)面,對(duì)巖體的力學(xué)性質(zhì)和變形特性起主控作用。軟弱夾層的存在對(duì)巖石結(jié)構(gòu)面的剪切強(qiáng)度往往有較大的弱化作用并影響巖石的穩(wěn)定性,本文根據(jù)Barton的20條經(jīng)典剖面曲線,選取其中JRC值為3、7、15和19的曲線,采用水泥、細(xì)砂和水按26:25:10質(zhì)量配比制成水泥砂漿在特制的模具里澆鑄含上述4種粗糙度的結(jié)構(gòu)面的類巖石試件,并分別充填砂粒、不同含水率的粘土等充填物,在0.5、1和1.5 MPa法向力作用下,在RYL-600巖石剪切流變儀上對(duì)類巖石材料充填結(jié)構(gòu)面進(jìn)行直剪試驗(yàn),研究不同情況下充填結(jié)構(gòu)面的剪切特性并分析各因素對(duì)剪切特性的影響,并采用PFC2D程序從細(xì)觀角度研究了充填物對(duì)粗糙結(jié)構(gòu)面剪切特性的影響。研究結(jié)果表明:(1)剪切應(yīng)力-剪切位移試驗(yàn)曲線大致可以分為無有峰型和有有峰型,JRC值較小以及低法向應(yīng)力下JRC值較大的充填結(jié)構(gòu)面,主要以無有峰型為主;無充填結(jié)構(gòu)和高法向應(yīng)力下JRC值較大的充填結(jié)構(gòu)面,主要以有有峰型為主;(2)通常情況下JRC值越大峰值剪應(yīng)力也越大,由于法向應(yīng)力的存在,增大了巖石結(jié)構(gòu)面間的摩擦力和爬坡阻力,從而增大了結(jié)構(gòu)面的剪應(yīng)力。充填物對(duì)峰值剪應(yīng)力有明顯的弱化作用,不同含水率土的弱化作用較砂粒而言更大,充填含水土結(jié)構(gòu)面中可塑態(tài)土對(duì)結(jié)構(gòu)面峰值剪應(yīng)力的弱化作用最為明顯;(3)引入弱化系數(shù)λ后得到修正JRC-JCS模型,通過該模型計(jì)算得出的最大剪應(yīng)力值的結(jié)果與試驗(yàn)值呈較好的線性關(guān)系;(4)通常情況下,JRC值越大,剪切過程中的法向位移也大,法向應(yīng)力的存在對(duì)結(jié)構(gòu)面的剪脹有一定的抑制作用,且法向應(yīng)力越大這種抑制作用越明顯。由于充填體的存在,結(jié)構(gòu)面間的剪脹或剪縮主要取決于充填物的壓縮量與凸臺(tái)剪脹量之間關(guān)系,充填物壓縮量大于凸臺(tái)剪脹量時(shí)整體表現(xiàn)為剪縮,壓縮量小于凸臺(tái)剪脹量時(shí)整體表現(xiàn)為剪脹;(5)結(jié)構(gòu)面剪脹模式大致可分為純剪脹、純剪縮和剪縮-剪脹三種模式,含充填體的結(jié)構(gòu)面發(fā)生剪縮的現(xiàn)象明顯要多于無充填的結(jié)構(gòu)面,而對(duì)于粗糙度較大的結(jié)構(gòu)面,剪縮-剪脹模式中占比較多;結(jié)構(gòu)面的峰值強(qiáng)度點(diǎn)的剪切位移在最大剪脹點(diǎn)剪切位移的0.72倍處左右;(6)結(jié)構(gòu)面間的微裂紋的發(fā)生主要集中在峰值剪切應(yīng)力附近,以剪切裂紋為主,由于充填物的存在,減少了結(jié)構(gòu)面微裂紋的產(chǎn)生,從而減少結(jié)構(gòu)面的破壞。
[Abstract]:Structural plane is a discontinuous plane widely distributed in natural rock mass, which plays a major role in controlling the mechanical properties and deformation characteristics of rock mass. The existence of weak intercalation often weakens the shear strength of rock structural plane and affects the stability of rock. According to 20 classical section curves of Barton, the curves with JRC values of 3 ~ 715 and 19 are selected and cement is used in this paper. Fine sand and water are used to make cement mortar into a special mould at 26:25:10 mass ratio to cast rock-like specimens containing the above four roughness structural surfaces, and filling sand and clay with different moisture content, respectively, under the normal force of 0.5 ~ 1 and 1.5 MPa, respectively. A direct shear test was carried out on the filling structure surface of rock-like material on RYL-600 rock shear rheometer. The shear characteristics of the filling structural plane under different conditions were studied and the influence of various factors on the shear characteristics was analyzed. The effect of filling on shear characteristics of rough structural plane was studied by PFC2D program from a meso point of view. The results show that: (1) the experimental curves of shear stress-shear displacement can be roughly divided into filling structural planes with no peak and small peak type and large JRC value under low normal stress, mainly with no peak; The filling surfaces with large JRC value under normal stress and without filling structure are mainly of peak type. (2) the larger the JRC value is, the greater the peak shear stress is, due to the existence of normal stress. The friction force and climbing resistance between the rock structure planes are increased, thus the shear stress of the structural plane is increased. The backfill has obvious weakening effect on the peak shear stress, and the weakening effect of soil with different moisture content is greater than that of sand. The weakening effect of plastic soil on the peak shear stress of structural plane is most obvious in filling soil and water bearing structural plane. (3) the modified JRC-JCS model is obtained by introducing the weakening coefficient 位. The maximum shear stress obtained by the model has a good linear relationship with the experimental value. (4) the larger the JRC value, the greater the normal displacement in the shear process. The existence of normal stress has a certain inhibitory effect on the shear expansion of the structural plane, and the greater the normal stress is, the more obvious the inhibition is. Because of the existence of the filling body, the shear expansion or shrinkage between the structural planes mainly depends on the relationship between the compression of the filling and the shearing expansion of the convex platform. When the compression of the filling is larger than the shearing expansion of the convex platform, the overall shearing shrinkage is observed. (5) the shear expansion mode of structural plane can be roughly divided into three modes: pure shear expansion, pure shearing shrinkage and shear-shearing expansion, and the phenomenon of shearing shrinkage in the structural plane containing filling body is obviously more than that in unfilled structural plane. However, the shear-shearing expansion mode accounts for more of the structural surfaces with larger roughness. The shear displacement of the peak strength point of the structural plane is about 0.72 times that of the maximum shear expansion point. (6) the occurrence of microcracks between the structural planes is mainly near the peak shear stress, and the shear crack is the main one, due to the existence of the filling. The formation of microcracks in the structural plane is reduced, thus the damage of the structural plane is reduced.
【學(xué)位授予單位】：湖南科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB302

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