【正文】 gain their original index as far as possible before the frozen samples are tested, the test results can not reflect the true facts obviously. Therefore, it is essential to consolidate the samples to the original degree of consolidation as far as possible before freezing them and testing. The test and application personnel have not fully realize this key point yet. ZJ290凍結(jié)粘土在 5℃ 、 10℃ 、15℃ 、 20℃ 和 25℃ 五種試驗(yàn)溫度、排氣排水條件下試驗(yàn)所得瞬時(shí) σ q值。隨著 p值增加，剪應(yīng)力峰值后都開始下降并不斷加速，即有冰融化發(fā)生。高壓 p值下冰融化到最后就會(huì)導(dǎo)致不同溫度下的這種剪應(yīng)力曲線應(yīng)全部趨向接近，而不是本圖中的這種曲線最后相互遠(yuǎn)離。 Frozen Lanzhou sand Triaxial tests at temperature 2, , 5 and 7℃ Constant axial strain rate %/min (cont.) The main points for tests of artificial frozen soil mechanical properties 國內(nèi)某凍土研究機(jī)構(gòu)對凍結(jié)粘土進(jìn)行了不同負(fù)溫、不同圍壓下的三軸剪切試驗(yàn)如圖 . Some results of triaxial shear tests on frozen clay under different confining pressure in different negative temperatures by a domestic research oganization (cont.) The main points for tests of artificial frozen soil mechanical properties 圖中顯示在同一負(fù)溫下，其試驗(yàn)凍結(jié)粘土在 1～ 10MPa下的三軸強(qiáng)度試驗(yàn)結(jié)果呈現(xiàn)不同尋常的特點(diǎn)：峰值偏應(yīng)力 (或三軸抗剪強(qiáng)度 )基本不變，莫爾圓包絡(luò)線幾乎呈水平線，三軸剪切強(qiáng)度可取作定值。這和我們所在溫度 10℃ 、不排氣條件下試驗(yàn)所得的三軸剪切強(qiáng)度數(shù)據(jù)相近 (圖 1中虛線 )，其實(shí)是正常的。s circle envelope is almost horizontal, under confined pressure from 1 to10 MPa in the same negative temperature. And its internal friction Angle φat 5, 10 ,15 ℃ is equal to or less than 0176。 (cont.) The main points for tests of artificial frozen soil mechanical properties 在深凍結(jié)井中除了凍土抗壓強(qiáng)度外，長時(shí)強(qiáng)度、蠕變特性極為重要，這些指標(biāo)決定著凍結(jié)鑿井的成敗。 While the tensile strength, shear strength and bending strength of frozen soil are sometimes very important except the pressive strength in municipal ground freezing engineering . The countermeasure to ground freezing heave and thaw settlement ? 在市政工程的地層凍結(jié)中，土壤的凍脹和融沉大小對關(guān)聯(lián)建/構(gòu)筑物影響至關(guān)重要。根據(jù)這種估算采取必要的措施。對于凍結(jié)時(shí)那些土壤內(nèi)產(chǎn)生水分不斷向凍結(jié)鋒面遷移而不斷集聚凍結(jié)成冰鏡體（凍敏性土），對于原土體來說體積增加了遷移來的水的體積加上這些液態(tài)水變成固態(tài)冰體積增加 9%，即增加了新遷移水 109%的體積（遷移水凍脹）。這種凍脹是一種在土壤凍結(jié)時(shí)形成一種勢（能量）使水能在連通的非常細(xì)小的土壤孔隙里不斷向凍結(jié)封面遷移，所謂“土水勢”。它由重力勢、壓力勢、滲壓勢、溫度勢、電力勢和磁力勢中的某些和組成。對于沉降要求很嚴(yán)的地方，可以采取跟蹤注漿等方式控制沉降量。副立井井筒施工到 472米深處發(fā)現(xiàn)巖層下部含水量很大而無法繼續(xù)施工，決定下部施工前先對開挖荒徑外進(jìn)行凍結(jié)封水，也就是從 472米深處往下凍結(jié)到深度 955m?，F(xiàn)在已經(jīng)開始凍結(jié)。管間用凍結(jié)止水。 ? Temporary palisade structure is steel tube act (pipe diameter of m), clear distance between pipes is between 20from 25 mm. The gaps between tubes are frozen as water cutoff. The freezing tubes are arranged along the circle contour line of the steel tubes in the steel tube diameter m. (隧道 ) Some new cases interested of GFM (tunnel)（ cont.） ? 凍結(jié)管設(shè)置在管幕鋼管內(nèi) ? The freezing tubes are arranged along the circle contour line of the steel tubes in the steel tube diameter m. Freezing pipe Ice wall thick Tube act Concrete in the tube 紅色為加熱管 red is heating pipes 結(jié)語 Conclusion ? 盡可能全面把握所有關(guān)聯(lián)的工程地質(zhì)和水文地質(zhì)、邊界條件 As far as possible to grasp of all related engineering geology, hydrogeology and all related boundary conditions ? 正確選擇凍土結(jié)構(gòu)模型 To chose frozen soil structure model correctly ? 正確把握凍土物理力學(xué)關(guān)鍵參數(shù)的試驗(yàn)方法 To correctly understand the test methods for physical and mechanical key parameters in the frozen soil ? 仔細(xì)研判凍土結(jié)構(gòu)關(guān)聯(lián)的所有不利因素 To analyze the permafrost carefully all the structural relationship factors ? 時(shí)刻記住凍土結(jié)構(gòu)的核心是冰 —— 隨時(shí)可變！ To keep in mind that ice is the core of frozen soil structure and it may change at any time! 致謝 Acknowledgements 感謝下列單位 : ? 煤炭科學(xué)研究總院 ? 港珠澳大橋管理中心 ? 鐵道第四設(shè)計(jì)研究院 Thanks to the following units, ? China Central Coal Mining Research Institute ? The Administration Center of the Hong Kong, zhuhai and Macau Bridge Construction ? The Railway Fourth Design and Research Institute