本文關鍵詞： 風化砂改良 膨脹土 物理特性 脹縮特性 強度特性 工后沉降　出處：《三峽大學》2014年碩士論文　論文類型：學位論文

【摘要】：在膨脹土地區(qū)修建公路時，往往需要對膨脹土進行改良處理，目前工程實踐中常用石灰、粉煤灰和水泥等無機結合料改良膨脹土，利用無機結合料改良膨脹土，可以改善膨脹土的工程性質，但是存在施工控制困難、污染環(huán)境、成本過高等不足之處。本文結合宜昌市風化砂廣泛分布的特點，依托小溪塔至鴉鵲嶺一級公路改建工程，對不同比例風化砂改良膨脹土的物理性質、脹縮特性以及力學強度特性進行了室內試驗研究，得到了不同摻砂比例下風化砂改良膨脹土的特性指標，以及摻砂比例對改良土工程特性的影響規(guī)律，同時結合小溪塔至鴉鵲嶺一級公路改建工程進行了現(xiàn)場試驗監(jiān)測。本文的主要結論如下： 對質量比0%、10%、20%、30%、40%、50%風化砂改良膨脹土的物理性質、脹縮特性和強度特性進行了研究。通過對物理性質研究可知，摻砂能夠改善膨脹土的含水特性、壓實特性、及超固結性，且改善的效果隨著摻砂比例的增加先增大后逐漸趨于平緩；通過對脹縮特性的研究表明，摻入風化砂能夠有效的抑制膨脹，改善膨脹土的收縮特性；改良膨脹土的脹縮指標隨著摻砂比例的增大逐漸減小，無荷膨脹率隨著摻砂比例的改變呈線性減��；當摻砂比例大于20%時，改良土的脹縮總率小于0.7%，自由膨脹率小于40%,達到路基施工技術規(guī)范對路基填料要求；通過對力學強度指標的研究可知，摻砂可以明顯的提高膨脹土的強度，達到路基填料的要求；摻入風化砂對于膨脹土的內摩擦角的影響較小，對膨脹土的黏聚力影響較大；隨著摻砂比例的增大，改良土的無側限抗壓強度和回彈模量先增大后減小，當摻砂比例為10%時，此時無側限抗壓強度和回彈模量達到最大值；隨著摻砂比例的增大，改良膨脹土的CBR值逐漸增大，且增長趨勢先快后慢。 綜合技術經濟指標分析，確定施工配合比，同時進行了試驗路段的鋪筑和現(xiàn)場試驗監(jiān)測。綜合考慮技術經濟指標，，確定摻入20%風化砂為施工配合比；同時對小溪塔至鴉鵲嶺一級公路風化砂改良膨脹土填筑路基連續(xù)3個月的工后沉降進行觀測，觀測結果顯示月平均沉降速率2.1mm，滿足設計小于3mm的要求，從第三周開始，該試驗路段路基的沉降基本趨于穩(wěn)定，從工程實際上驗證了風化砂改良膨脹土的可行性。
[Abstract]:In the construction of highway in expansive soil area, it is often necessary to improve the expansive soil. In current engineering practice, inorganic binders such as lime, fly ash and cement are commonly used to improve expansive soil, and inorganic binder is used to improve expansive soil. The engineering properties of expansive soil can be improved, but there are some shortcomings such as difficult construction control, environmental pollution, high cost and so on. According to the characteristics of widespread distribution of weathered sand in Yichang City, this paper relies on the reconstruction project of Xiaoxita to Yakueling first class highway. The physical properties, dilatation and shrinkage characteristics and mechanical strength characteristics of expansive soil improved by weathered sand with different proportion were studied in laboratory. The characteristic indexes of weathered sand modified expansive soil with different proportion of sand were obtained. The influence of sand ratio on the characteristics of the improved soil is also studied. Combined with the first class highway reconstruction project from Xiaoxita to Ya que Ling, the field test monitoring is carried out. The main conclusions of this paper are as follows:. In this paper, the physical properties, dilatation and shrinkage characteristics and strength characteristics of the expansive soil improved by 50% weathered sand are studied. Through the study of the physical properties, it can be seen that the mixing sand can improve the water-bearing, compaction, and over-consolidation properties of the expansive soil. With the increase of the ratio of sand to sand, the effect of improvement increases first and then tends to be gentle. The study of dilatation and shrinkage characteristics shows that the addition of weathered sand can effectively inhibit the expansion and improve the shrinkage characteristics of expansive soil. The swelling and shrinkage index of the improved expansive soil decreases with the increase of the ratio of sand to sand, and the load free expansion rate decreases linearly with the change of the ratio of sand to sand, and when the ratio of sand to sand is greater than 20, The total expansion rate of the improved soil is less than 0.7 and the free expansion rate is less than 40, which can meet the requirements of the subgrade filling in the technical specifications of subgrade construction. Through the study of the mechanical strength index, it can be seen that the strength of the expansive soil can be obviously increased by adding sand, The influence of weathering sand on the internal friction angle of expansive soil is small, and on the cohesion of expansive soil is greater, with the increase of sand ratio, the unconfined compressive strength and modulus of resilience of the improved soil first increase and then decrease. When the sand ratio is 10, the unconfined compressive strength and modulus of resilience reach the maximum; with the increase of the ratio of sand, the CBR value of the improved expansive soil increases gradually, and the growth trend is first fast and then slow. According to the analysis of the technical and economic indexes, the construction mix ratio is determined, and the paving and field test monitoring of the test section are carried out. Considering the technical and economic indexes, the mixing of 20% weathered sand is determined as the construction mix ratio. At the same time, the post-construction settlement of weathered sand improved expansive soil filling subgrade for 3 months on the first class highway from Xiaoxita to Ya que Ling is observed. The results show that the average monthly settlement rate is 2.1 mm, which meets the requirement of design less than 3 mm and starts from the third week. The settlement of the roadbed in this experimental section tends to be stable, and the feasibility of improving expansive soil by weathering sand is verified by the project.
【學位授予單位】：三峽大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TU443;TU411

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