本文選題：土的結(jié)構(gòu)性　切入點(diǎn)：靈敏度　出處：《太原理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：土的結(jié)構(gòu)性是決定土體力學(xué)特性的一個極為重要的內(nèi)在因素。本文通過室內(nèi)無側(cè)限抗壓強(qiáng)度試驗(yàn)與錐入度試驗(yàn)分別對粉土的靈敏度和錐入度之比進(jìn)行了研究，并且從這兩個方面來分析土體受到擾動和飽和度變化時土體結(jié)構(gòu)性的變化規(guī)律。試驗(yàn)結(jié)果表明： （1）當(dāng)粉土受到浸水的影響時從靈敏度隨飽和度的變化規(guī)律可知，土體飽和度在70%左右土對外荷載的反應(yīng)最靈敏，此時靈敏度取得最大值，而且土體擾動前后強(qiáng)度變化明顯，在受到外界荷載的作用下土體容易發(fā)生破壞。 （2）在應(yīng)變靈敏度的試驗(yàn)結(jié)果分析中，通過試驗(yàn)可知應(yīng)變靈敏度隨應(yīng)變曲線變化的峰值點(diǎn)代表著原狀土有裂縫出現(xiàn)的時刻。峰值點(diǎn)以前土體的變形為塑性變形，峰值點(diǎn)以后土體逐漸失去原有的結(jié)構(gòu),伴隨著裂縫的不斷開展，原狀土與重塑土之間抗壓能力的差距越來越小，相應(yīng)的應(yīng)力的比值逐漸減小曲線下降。 （3）在應(yīng)力靈敏度的試驗(yàn)結(jié)果分析中應(yīng)力靈敏度隨應(yīng)變變化曲線圖沒有出現(xiàn)峰值點(diǎn)，曲線呈單調(diào)上升的趨勢，并且隨著壓力的增加原狀土的變形速率大于重塑土的變形速率。因此，同一應(yīng)力狀態(tài)下應(yīng)力靈敏度比值也越來越大，曲線圖也客觀地反映了加荷對土體結(jié)構(gòu)的影響。 （4）從三種靈敏度的比較分析可知，應(yīng)變靈敏度側(cè)重于土的結(jié)構(gòu)強(qiáng)度，比值越大說明原狀土與重塑土的強(qiáng)度差越大，因此土擾動前后受到外荷載作用時土體的反應(yīng)越靈敏。應(yīng)力靈敏度則側(cè)重于土的變形能力，比值越大說明隨著力在相同微小增量的情況下原狀土變形的變化增速要比重塑土變形的變化增速大。通常定義的靈敏度只是單一的通過土體破壞后原狀土與重塑土的強(qiáng)度比來反映土靈敏度的強(qiáng)弱。 （5）在錐入度之比的數(shù)值分析中，錐入度的比值隨著飽和度由低到高的變化，其比值先呈現(xiàn)出下降的趨勢，大概在飽和度達(dá)到70%左右比值達(dá)到最小值，然后隨著飽和的度的增加曲線呈現(xiàn)出上升的趨勢，，而且不論飽和度如何變化錐入度的比值都小于1。 （6）錐入度之比與三種靈敏度的比較分析表明，錐入度之比與通常定義的靈敏度，二者在表現(xiàn)土體結(jié)構(gòu)性時有著對應(yīng)的關(guān)系，曲線圖近似為軸對稱圖形，并且靈敏度越大土體的結(jié)構(gòu)強(qiáng)度越明顯，相反錐入度之比越小土的結(jié)構(gòu)強(qiáng)度也越明顯；從整體上來說錐入度之比與應(yīng)變靈敏度最大值的曲線圖存在著一定的對應(yīng)關(guān)系，而從曲線上的每個點(diǎn)來說，土體應(yīng)變靈敏度取到最大值時土體未完全破壞，土的結(jié)構(gòu)強(qiáng)度沒有得到完全釋放，錐入度之比的每個值反映了原狀土與重塑土抵抗剪切破壞的能力；在錐入度之比與應(yīng)力靈敏度隨飽和度變化的規(guī)律中，應(yīng)力靈敏度的每個最大值變化不大，因此受飽和度變化的影響比較有限，而錐入度之比值隨著飽和度的增加卻呈現(xiàn)出先減小后增大的變化規(guī)律，因此錐入度之比受飽和度變化的影響比較明顯。
[Abstract]:The structure of soil is a very important internal factor to determine the mechanical properties of soil. The sensitivity and cone penetration ratio of silt are studied by the unconfined compressive strength test and cone penetration test in this paper. And from these two aspects to analyze the soil structure change law when the soil is disturbed and the saturation changes. The experimental results show that:. 1) when silty soil is affected by soaking water, it can be seen from the law of sensitivity changing with saturation that soil saturation is the most sensitive when soil saturation is about 70%, and the sensitivity reaches the maximum at this time, and the strength of soil changes obviously before and after disturbance. Soil is liable to damage under external load. 2) in the analysis of the test results of strain sensitivity, it can be seen that the peak point of strain sensitivity changing with strain curve represents the time when cracks occur in undisturbed soil. The deformation of soil before peak point is plastic deformation. After the peak point the soil gradually loses its original structure. With the continuous development of cracks the gap between the compressive capacity of the undisturbed soil and the remolded soil becomes smaller and smaller and the corresponding stress ratio decreases gradually. 3) in the analysis of the test results of stress sensitivity, there is no peak point in the curve of stress sensitivity changing with strain, and the curve shows a monotone rising trend. With the increase of pressure, the deformation rate of undisturbed soil is larger than that of remolded soil. Therefore, the ratio of stress sensitivity under the same stress state is also increasing, and the curve also objectively reflects the effect of loading on soil structure. 4) from the comparative analysis of the three kinds of sensitivities, it can be seen that the strain sensitivity focuses on the structural strength of the soil, and the greater the ratio is, the greater the difference between the strength of the undisturbed soil and the remolded soil is. Therefore, the more sensitive the response of soil to external load before and after disturbance, the more sensitive the stress sensitivity is to the deformation ability of soil. The larger the ratio is, the faster the deformation rate of undisturbed soil with the same small increment of force is higher than that of the deformation of remolded soil. The strength ratio of the soil reflects the sensitivity of the soil. 5) in the numerical analysis of the ratio of cone penetration, the ratio of cone penetration decreases with the change of saturation from low to high, and the ratio reaches the minimum value at about 70%. Then the curve shows an upward trend with the increase of saturation, and the ratio of cone penetration is less than 1. The comparison and analysis of the ratio of cone penetration and three kinds of sensitivity show that the ratio of cone penetration to the commonly defined sensitivity has a corresponding relationship in the performance of soil structure, and the curve is approximately axisymmetric. The larger the sensitivity of soil is, the more obvious the structural strength of soil is, and the smaller the ratio of cone penetration is, the more obvious is the structural strength of soil, and on the whole, the ratio of cone penetration to the curve of maximum strain sensitivity has a certain corresponding relationship. From each point on the curve, when the strain sensitivity of the soil reaches the maximum, the soil is not completely destroyed, and the structure strength of the soil is not completely released. Each value of the ratio of cone penetration reflects the ability of the undisturbed soil and the remolded soil to resist shear failure. In the law that the ratio of cone penetration to stress sensitivity varies with saturation, each maximum value of stress sensitivity does not change much, so it is limited by the change of saturation. However, the ratio of cone penetration decreases first and then increases with the increase of saturation, so the ratio of cone penetration is obviously affected by the change of saturation.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU411

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