紅層軟巖變形特性及基床系數(shù)取值試驗(yàn)研究

周其健 鄭立寧 鄧榮貴 陳繼彬 羅益斌

摘要：巖體變形特性及基床系數(shù)與基礎(chǔ)內(nèi)力、最終變形量和變形的均勻性直接相關(guān)，合理確定基床系數(shù)值對(duì)高層特別是超高層建筑至關(guān)重要。以成都市某超高層建筑論證為依托，針對(duì)建筑物持力層中風(fēng)化泥質(zhì)軟巖，在井下平洞內(nèi)進(jìn)行不同壓板尺寸和形狀的平板載荷試驗(yàn)，并取得原位試樣進(jìn)行室內(nèi)巖塊單軸抗壓強(qiáng)度、常規(guī)三軸壓縮試驗(yàn)和直接剪切試驗(yàn)，根據(jù)室內(nèi)及原位試驗(yàn)資料分析了巖體單軸抗壓強(qiáng)度、彈性模量、承壓板尺寸與基床系數(shù)的關(guān)系。結(jié)果表明：地基基床系數(shù)具有隨地基巖石單軸抗壓強(qiáng)度增加而增加的趨勢(shì);較小承壓板試驗(yàn)數(shù)據(jù)離散性較大，較大壓板試驗(yàn)數(shù)據(jù)離散性較小;如果紅層軟巖基床系數(shù)按照規(guī)范建議的黏土或砂土經(jīng)驗(yàn)公式進(jìn)行修正，會(huì)引起較大誤差;紅層軟巖（中等風(fēng)化泥巖）地基的基床系數(shù)與載荷板尺寸間呈雙曲線型經(jīng)驗(yàn)關(guān)系，據(jù)此建議對(duì)建筑物紅層軟巖地基基床系數(shù)進(jìn)行修正;對(duì)紅層軟巖采用500 mm方形承壓板試驗(yàn)獲取的基床系數(shù)離散性較小。

關(guān)鍵詞：紅層軟巖;變形;基床系數(shù);平板載荷試驗(yàn);地基

中圖分類號(hào)：TU443 文獻(xiàn)標(biāo)志碼：A 文章編號(hào)：20966717（2020）04006007

收稿日期：20190924

基金項(xiàng)目：四川省科學(xué)技術(shù)廳資助項(xiàng)目（2019GFW176）

作者簡(jiǎn)介：周其?。?979 ），男，博士生，高級(jí)工程師，主要從事特殊巖土體工程特性研究，Email：280460270@qq.com。

Received：20190924

Foundation items：Science & Technology Foundation of Sichuan Province （No. 2019GFW176）

Author brief：Zhou Qijian （1979 ）， PhD candidate， senior engineer， main research interests： engineering characteristics of special rock and soil， Email： 280460270@qq.com.

Experimental study on deformation characteristics and coefficient of subgrade reaction of red mudstone

Zhou Qijian1，2， Zheng Lining2， Deng Ronggui1， Chen Jibin2， Luo Yibin2

（1.School of Civil Engineering， Southwest Jiaotong University， Chengdu 611756， P.R. China， 2. China Southwest Geotechnical Investigation & Design Institute Co.， Ltd.， Chengdu 610052， P.R. China）

Abstract： The deformation characteristics of rock mass and the coefficient of subgrade reaction are directly related to the internal force， final deformation and deformation uniformity of foundation. Determination of reasonable coefficient of subgrade reaction is important for highrise buildings， especially super highrise buildings. Taken a superhighrise building in Chengdu as example， plate loading tests of redbed soft rock foundation with different plate sizes and shapes were carried out. Besides， the uniaxial compressive strength test （UCS）， conventional triaxial compression test and direct shear test of redbed mudstone were carried out. Based on the results of laboratory and insitu test， the relationship between UCS， elastic modulus， bearing plate size and coefficient of subgrade reaction were analyzed. The results show that the coefficient of subgrade reaction has a tendency to increase with ?UCS of rock， and the smaller the bearing plate size is， the more discrete test data will be obtained. The coefficient of subgrade reaction of redbed mudstone obtained by 500 mm square bearing plate test is recommended. It is found that the coefficient of subgrade reaction of redbed mudstone layer has a hyperbolic empirical relationship with the plate size. If the coefficient of subgrade reaction of redbed mudstone layer is modified according to the empirical formula of clay or sand recommended by the code， it will cause a large error. Therefore， it is suggested that the coefficient of subgrade reaction is modified based on the hyperbolic empirical relationship.

根據(jù)現(xiàn)場(chǎng)載荷試驗(yàn)，統(tǒng)計(jì)各試驗(yàn)點(diǎn)位比例界限、比例界限對(duì)應(yīng)變形、基床系數(shù)以及天然單軸抗壓強(qiáng)度（Uniaxial Compressive Strength，簡(jiǎn)稱UCS）試驗(yàn)結(jié)果見表2?！?br>