1、再說地層凍結法紀念地層凍結法150周年Some New Words On Ground Freezing Methodin memory of 150th anniversary application of GFM,深圳市地鐵集團有限公司 陳湘生博士 上海，05. 2012 CHEN Xiangsheng, Ph. D. Shenzhen Metro Co. (Group), Ltd. Shanghai, 05. 2012,目錄 Contents,概述 Overview 地層凍結法關鍵要素 The key elements for GFM 人工凍土力學參數試驗注意事項 The main po

2、ints for tests of artificial frozen soil mechanical properties 地層凍脹融沉問題及對策 The countermeasure to ground freezing heave and thaw settlement 最新地層凍結案例 Some new cases interested of GFM,1.概述 Overview,追索求源 Originating 地層凍結法源于天然凍結現象。1850年代蒸汽壓縮式冷凍機發明后，人類第一次使用地層凍結法是1862年在Wales基坑中；1880年德國工程師Poetch首先提出地層凍結法原理，

3、并于1883年在德國阿爾巴里德煤礦成功地采用凍結工法建造103m深的豎井。我國第一次應用地層凍結法是1955年開灤煤礦林西風井（直徑5m，凍深105m）。 Ground freezing method (GFM) originated from natural freezing phenomenon. It was the first time in 1862 that GFM was used in Wales foundation pit after invention of steam compression refrigerator in1850 s. The German engin

4、eer, Poetch, proposed first the principle of GFM in 1880, and then this method was successfully used in sinking a shaft in depth of 103m in Germanys coal mine in 1883. It was in 1955 that GFM was used in sinking Linxi air shaft (dia. 5m and frozen depth of 105 m) in Kailuan Coal Mine first in China.

5、,1.概述 Overview (Cont.),核心是把地層里的水變成冰 The key of GFM is to change the water in soil into ice. 地層凍結的核心是把地層里幾乎“沒有強度”的水變成“強度極高且可以粘結土顆粒”的冰，而且冰的強度和彈性模量隨負溫度降低而增大。由此可以根據對凍土結構要求而隨時調節凍結溫度來確保凍土結構的穩定。 The core of GFM is to change no strength of water the strata into ice of high strength and power bonding soil pa

6、rticle“. Moreover, both strength and elasticity modulus of ice increase with decrease in negative temperature. This may, according to the requirements of frozen soil structure, adjust the freezing temperature in frozen soil structure to ensure its stability at any time.,1.概述 Overview (Cont.),核心是把地層里

7、的水變成冰(Cont.) The key of GFM is to change the water in soil into ice. 所以，要了解水凍成冰的要素：地層里水的冰點、含鹽、地層溫度、水力聯系和周邊影響溫度的邊界條件等，還有凍土結構相關連影響穩定的邊界條件。 在設計凍土結構時，要充分了解其受力狀態、簡化的受力模型、需要的力學指標等。還有土壤的凍脹和融沉特性 First things first is to understand the freezing temperature of the water in the stratum, its salt, stratum forma

8、tion temperature, hydraulic relationship and surrounding heat influence, the boundary conditions of temperature, and moreover the boundary conditions of the frozen structure. Then all these elements must fully be understood when a frozen structure is designed: its stress state, the simplified model,

9、 the mechanics index needed, and etc. Meanwhile, the characteristics must be kept in mind of freezing heave and thaw settlement of soil.,1.概述 Overview (Cont.),帶領全球的中國地層凍結 Ground Greezing in Mainland China Leading the global 截至2011年年底，中國大陸地區利用地層凍結法完成鑿井約790個，總里程約180km；最大凍結深度達到955m。完成市政工程凍結項目98個（其中地鐵工程

10、超過70個），最長水平凍結長度到達147m。各項指標領先全球。 By the end of 2011, GFM has successfully been used in China mainland sunk shafts 790 with total mileage more than 180km and maximum frozen depth of 955m, and finished municipal engineering projects 98 (including the subway frozen projects more than 70) with the longes

11、t horizontal freezing length of 147 m. All technical indexes lead in the world.,2. 地層凍結法關鍵要素 The key elements for GFM,工程地質和水文地質及關鍵物理力學指標 The information of engineering geology and hydrogeology, and the key physical and mechanical indexes 設計要素 The key factors of design 施工要素 The key elements for execu

12、tion 管理等關聯要素 The key points for management,2. 地層凍結法關鍵要素The key elements for GFM (cont.),工程地質和水文地質及關鍵物理力學指標 The information of engineering geology and hydrogeology, and the key physical and mechanical indexes 1.施工范圍內及關聯的地層分布、水位（含氣?）含水層及水力聯系、流速流向、含鹽量、隔水層、土的基本力學性質、比熱、熱傳導系數、潛熱、結冰溫度等 The related strata d

13、istribution, stage (air ball?), aquifer location and hydraulic connection, Flow velocity and direction, salt concentration in the soil, aquiclude, the basic mechanical properties of soil, specific heat and thermal conductivity, the latent heat, freezing temperature, etc 2.土壤凍脹和融沉（凍土解凍）；單軸抗壓、抗拉、抗剪(粘聚

14、力、內摩擦角)、三軸強度、變形模量、泊淞比（受溫度、含水量、未凍水含量、粒徑、孔隙率、荷載、時間等影響） Frost heaving and thaw settlement (thawing); Uniaxial compressive, tensile and shear strength (cohesion, friction angle), triaxial strength, deformation modulus and poisson ratio (influenced by temperature, water content, unfrozen water content, p

15、article diameter, pore ratio, loading, and loaded time, etc),2. 地層凍結法關鍵要素(cont.) The key elements for GFM,設計要素The key factors of design 首先是建立凍土結構受力模型（純凍土結構、和其它結構共同承載、作為其它結構承載的封水等） First step is to chose a frozen structure bearing model (pure frozen soil structure, or other structure jointed with fro

16、zen soil, or as water shutoff (frozen soil) for other structure) 其次是在所選結構模型下全面考量全過程可能影響凍土強度、凍土結構本身可能影響周邊環境或者影響維護結構本身穩定和安全的可能性 Second is to comprehensively consider the possibility of affecting the permafrost strength in the chosen frozen structure model through the process, frozen soil structure its

17、elf may affect the related environment or influence the stability and security of the frozen structure itself.,2. 地層凍結法關鍵要素(cont.) The key elements for GFM,設計要素The key factors of design (cont.) 再次是按所選凍土結構受力模型進行對應的凍土力學性能試驗而獲得必要的計算參數、并對凍土結構的凍脹融沉進行量化、針對計算結構進行措施補充（包括所有檢測監控） Once again is to obtain the n

18、ecessary parameters of the frozen soil by carrying out the corresponding mechanical test according to selected frozen soil structure bearing model, to quantitatively calculate freezing heave and thaw settlement of the related strata, and to supplement measures for the frozen soil structure （includin

19、g all the detection monitoring） 最后就是實施這一設計進行施工組織設計 The last is to carry out the construction organization design.,2. 地層凍結法關鍵要素 The key elements for GFM (cont.),施工要素 The key elements for execution 凍結孔施工、凍結管安裝以及質量的檢測； Freezing pipe hole drilling, the pipe installation, and the final result inspection

20、地層內溫度檢測和鹽水等檢測系統的可靠性； Inspection of the system reliability of both the temperature measuring in the frozen soil and the brine data logging (temperature and flow) 達到凍結設計要求的檢測和確認 Inspection and confirmation realizing the frozen structure design requirements 凍脹檢測和控制、融沉監測和控制； Frost heaving measuring and

21、control, thaw settlement monitoring and control; 開挖和支護，凍土結構變形實時檢測 Excavating and lining, frozen soil structure deformation monitoring in situ,2. 地層凍結法關鍵要素(cont.) The key elements for GFM,管理等關聯要素 The key points for management 凍結法是面對高風險地方的工法，故對于上述各個環節必須進行多次反復檢查和檢驗，動態監測控制、精細化施工、嚴格監理管理,達到安全可靠。 Ground fr

22、eezing method is a some kind of anagraph to high-risk problems, therefor the above each procedure must be inspected and confirmed repeatedly in order to realize safety and reliability by monitoring and controlling in time, elaborately constructing and consultant managing strictly.,3.人工凍土力學參數試驗注意事項Th

23、e main points for tests of artificial frozen soil mechanical properties,礦山凍結鑿井中凍土試驗 Frozen soil mechanical property tests for frozen shaft lining 市政工程中地層凍結凍土試驗 Frozen soil mechanical property tests for municipal frozen engineering 上述兩個方面對凍土物理力學指標的要求是不完全相同的。The requirements for the above two aspects

24、are not completely the same of the frozen soil physical and mechanical indexes,3.人工凍土力學參數試驗注意事項(cont.) The main points for tests of artificial frozen soil mechanical properties,礦山凍結鑿井中凍土試驗 Frozen soil mechanical property tests for frozen shaft lining 全面正確認識凍土：凍土是由固相（土壤顆粒、冰）、液相（未凍水）、氣相（氣泡）組成多相介質（非飽和土

25、） 。土樣取樣、凍土試樣是否固結、是否達到固結度就是關鍵了。 Overall correct understanding of frozen soil: frozen soil is composed of solid phase (soil particles, ice), liquid (not cold water), air phase (bubble), that is a some kind of a multiphase medium （unsaturated soil）. The key is how to sample natural soil, whether consol

26、idate the frozen soil samples and if to meet the degree of consolidation.,3.人工凍土力學參數試驗注意事項(cont.) The main points for tests of artificial frozen soil mechanical properties,礦山凍結鑿井中凍土試驗 Frozen soil mechanical property tests for frozen shaft lining 由于礦山鑿井深度比較深，土樣取樣后應力釋放而體積和容重都發生變化。如果在凍土試驗前不盡可能恢復到原來指標，顯

27、然所得結果不能反映真實情況。因此，在凍結前對式樣進行固結并盡可能到達原來的固結度是非常必要的。到目前，試驗和工程應用人員還沒有充分認識到這一點。 The appearance density and volume of samples are changed because of stress release after sampling and depth of a shaft. If the soil samples do not regain their original index as far as possible before the frozen samples are tes

28、ted, 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凍結粘土在-

29、5、-10、-15、-20 和-25五種試驗溫度、排氣排水條件下試驗所得瞬時3、q值。將這些數據繪于p-q坐標平面如圖所示,p=(1+23)/3 q=1-3,本試驗僅限于 313.25MPa,3.人工凍土力學參數試驗注意事項(cont.) The main points for tests of artificial frozen soil mechanical properties,ZJ290 frozen clay triaxial tests under drainage and un-drainage condition Constant axial strain rate 0.1%/

30、min,3.人工凍土力學參數試驗注意事項(cont.) The main points for tests of artificial frozen soil mechanical properties,蘭州凍砂瞬時三軸剪切強度結果。隨著p值增加，剪應力峰值后都開始下降并不斷加速，即有冰融化發生。圖中看到，剪應力峰值過后隨著p值不斷升高而加速這種冰的融化。高壓p值下冰融化到最后就會導致不同溫度下的這種剪應力曲線應全部趨向接近，而不是本圖中的這種曲線最后相互遠離。這種最后遠離說明負溫和“冰融”作用都很大，這與實際情況不符。,Frozen Lanzhou sand Triaxial tests a

31、t temperature -2, -3.5, -5 and -7 Constant axial strain rate 6.7%/min,3.人工凍土力學參數試驗注意事項(cont.)The main points for tests of artificial frozen soil mechanical properties,國內某凍土研究機構對凍結粘土進行了不同負溫、不同圍壓下的三軸剪切試驗如圖.,Some results of triaxial shear tests on frozen clay under different confining pressure in diffe

32、rent negative temperatures by a domestic research oganization,3.人工凍土力學參數試驗注意事項(cont.)The main points for tests of artificial frozen soil mechanical properties,圖中顯示在同一負溫下，其試驗凍結粘土在110MPa下的三軸強度試驗結果呈現不同尋常的特點：峰值偏應力(或三軸抗剪強度)基本不變，莫爾圓包絡線幾乎呈水平線，三軸剪切強度可取作定值。圖顯示：凍結固結粘土在-5，-15試驗溫度下的內摩擦角0；即其三軸抗剪強度與圍壓無關。這和我們所在溫度-

33、10、不排氣條件下試驗所得的三軸剪切強度數據相近(圖1中虛線)，其實是正常的。 Some unusual features can be found that triaxial strength of the clay are almost constant, or Mohrs circle envelope is almost horizontal, under confined pressure from 1 to10 MPa in the same negative temperature. And its internal friction Angle at -5, -10 ,-15

34、is equal to or less than 0, or the triaxial strength is not related to confined pressure. These kinds of so called “unusual features ” are just usual, all are the same as the triaxial shear strength data that we found under un-drainage of air and water at -10 (the dotted line).,3.人工凍土力學參數試驗注意事項(cont

35、.)The main points for tests of artificial frozen soil mechanical properties,在深凍結井中除了凍土抗壓強度外，長時強度、蠕變特性極為重要，這些指標決定著凍結鑿井的成敗。 Both the long-term strength and creep property of frozen soil are very important except the compressive strength, these parameters decide the success of the freeze shaft lining.

36、而在市政工程的地層凍結中，除了凍土抗壓強度外，有時候的抗拉強度、抗剪強度、抗彎強度極為重要。 While the tensile strength, shear strength and bending strength of frozen soil are sometimes very important except the compressive strength in municipal ground freezing engineering .,4.地層凍脹融沉問題及對策The countermeasure to ground freezing heave and thaw sett

37、lement,在市政工程的地層凍結中，土壤的凍脹和融沉大小對關聯建/構筑物影響至關重要。因此，在那些凍敏性土壤中應用凍結法，要特別注意相關聯建/構筑物安全要求和土壤本身凍脹和融沉特性，通過試驗和工程類比估算出凍脹和融沉量。根據這種估算采取必要的措施。 The magnitude both soil frost heaving and thaw settlement is very important to the related buildings/structures in municipal ground freezing. Therefore, more attention must b

38、e paid to the related buildings/structures safety requirements and soil itself frost heaving and thaw characteristics while GFM is applied in the freezing sensitive soil. Some necessary measures may be taken for the safety on the base of the estimated quantity of frost heaving and thaw settlement th

39、rough test and engineering analogy.,4.地層凍脹融沉問題及對策The countermeasure to ground freezing heave and thaw settlement,凍脹的主要原因是液態水凍結后變成固態冰,其體積增加9%產生“凍脹”。對于凍結時那些土壤內產生水分不斷向凍結鋒面遷移而不斷集聚凍結成冰鏡體（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水變成固態冰體積增加9%，即增加了新遷移水109%的體積（遷移水凍脹）。前者叫土體“原位凍脹”，后者叫“遷移水凍脹”或者叫 “分凝凍脹” The main reason o

40、f frost heaving is because its volume increases 9% when the water (liquid) changes into ice (solid) after freezing. The volume of the new migrated water increases 109% (the volume of the new migration water 100% plus its frost heaving 9%) for those kinds of freezing sensitive soils in which water mi

41、grates continuously to the freezing fringe where some ice lens come out constantly by water gathering. The former is called “original frost heaving, the latter is called “migrated water frost heaving or segregating condensation frost heave,4.地層凍脹融沉問題及對策The countermeasure to ground freezing heave and

42、 thaw settlement,在工程中原位凍脹很難消除（除非對土壤孔隙水做某種處理），主要是盡可能減少遷移水凍脹。這種凍脹是一種在土壤凍結時形成一種勢（能量）使水能在連通的非常細小的土壤孔隙里不斷向凍結封面遷移，所謂“土水勢”。它是一項目前還不能完全清晰表達的物理量。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。 It is very difficult to eliminate the original frost heaving (unless doing something with the soil pore water) in the engineering,

43、 while mainly to reduce migrated water frost heaving. This kind of frost heave is caused by a kind of a potential (energy) gathered when freezing which drives water migrating to the freezing fringe through micro hydraulic capillary in freezing sensitive soil. This potential is so-called “water poten

44、tial in soil” , which has not yet distinctly expressed some kind of physical quantity. It consists of some sum of gravity potential, pressure potential and seepage pressure potential, temperature differential, electric potential and magnetic potential.,4.地層凍脹融沉問題及對策The countermeasure to ground freez

45、ing heave and thaw settlement,速凍法：快速降溫使凍結速度超過水分遷移所需勢形成的速度，使水分來不及遷移 Instant frozen method: fast freezing causes water freezing speed faster than that of the potential formed for migration in order to make water too late to migrate. 動態平衡式凍結法：達到凍結厚度后控制制冷量使凍土不再發展，從而減小水分遷移 Balanced freezing in time metho

46、d: to control refrigerating capacity when the freeze thickness has been formed for reducing water migration 土壤改良法：凍結前對土壤進行某種改良，達到阻礙水力通道的目的 Soil improvement method: to conduct some improvement on soil before freeze to block the hydraulic capillary.,4.地層凍脹融沉問題及對策The countermeasure to ground freezing h

47、eave and thaw settlement,把凍脹控制了，融沉就基本控制了8090%。對于沉降要求很嚴的地方，可以采取跟蹤注漿等方式控制沉降量。 The thaw settlement will be reduced by 80-90% if migrated water frost heave has been totally blocked. Sometimes settlement tracked grouting may be carried out for the place where settlement control is strict.,5.最新地層凍結案例(豎井)S

48、ome new cases interested of GFM（shaft）,我國最深凍結井(也是世界最深凍結井，下部凍結) 核桃峪礦井位于甘肅省慶陽市正寧縣周家鄉，礦井建設規模為1200萬噸/年。副立井井筒施工到472米深處發現巖層下部含水量很大而無法繼續施工，決定下部施工前先對開挖荒徑外進行凍結封水，也就是從472米深處往下凍結到深度955m。 Heitaoyu Service shaft, located in Zhoujia Disitrict, Zhengning County, Gansu Province, is 955m deep, the deepest frozen in

49、the world with annual output 12 million tons/year. The shaft, lining to depth of 472m where underground water was encountered, have to be sunk by GFM from the depth of 472m to 955m. However, the freezing holes were drilled from the surface to the depth of 955m.,5.最新地層凍結案例（豎井）Some new cases intereste

50、d of GFM (shaft)（cont.）,井筒凈直徑9m，開挖荒徑10.413.4m，凍結孔布置圈徑19.4m凍結孔深度(深孔/淺孔) 955/856m，凍結孔(深孔/淺孔)個22/22凍結孔開孔間距1.385m，凍結管規格168mm，巖石凍結的凍結壁設計厚度4m，凍結壁平均溫度-8鹽水溫度-30。現在已經開始凍結。 The excavated diameter is about 10.4 13.4 m with net diameter 9 m and freezing hole arranged circle diameter 19.4 m. The freeze hole dept

51、hs are 955/856 m (22 deep holes/22 shallow holes), respectively, and freezing hole spaces 1.385 m with total 22+22 freezing holes. The diameter of freezing pipe is 168 mm. The rock designed thickness of frozen rock wall is 4m and frozen wall average temperature is -8 with the brine temperature is about -30 . The refrigerator station has started operation.,核桃峪礦井地質柱狀圖The service shaft geologi