Effects of a simulated freezing construction environment on the mass concrete performance
-
摘要: 模擬大體積混凝土在凍結法施工環境的狀態，將混凝土澆筑7 h后施加?5/60 ℃和?5/70 ℃溫差，測試施加模擬環境后混凝土的超聲波參數、抗壓強度、劈裂抗拉強度、氯離子擴散系數和沖擊傾向性，分析混凝土的掃描電鏡微觀形貌。結果表明，凍結施工環境對于混凝土內部會造成一定的損傷，且平行于加溫方向的損傷要大于垂直方向，C50混凝土的損傷大于C70混凝土，溫度梯度會加劇混凝土內部的損傷。模擬凍結環境會對混凝土抗壓強度、劈裂抗拉強度、氯離子滲透性能和沖擊傾向性造成不利影響，溫差與性能降低率正相關，且這種影響對于低強度混凝土更加顯著。模擬凍結環境造成混凝土試塊的內部微觀結構不均勻，低溫端混凝土結構比較疏松，高溫端結構比較致密，導致部分混凝土性能的降低。Abstract: Exhausted shallow resources have turned mining into deep mining, with the mining depth of most mines under construction being more than 1000 m. With the continuous increase of the mining depth of mineral resources, the thickness and strength grade of the shaft lining concrete increases, resulting in higher hydration heat. The freezing method is usually used in deep well construction, resulting in a high temperature on one side and a low temperature on the other side of the shaft wall concrete. The influence law of this environment on concrete needs to be studied. It is of great theoretical significance for deep well construction and service safety to find out the change law of the shaft wall concrete performance under a freezing construction environment. The temperature difference between ?5/60 ℃ and ?5/70 ℃ was applied to simulate the state of the mass concrete in the freezing method construction environment. The ultrasonic parameters, compressive strength, splitting tensile strength, chloride diffusion coefficient, and bursting liability of concrete under the simulated environment were studied, and the scanning electron microscope of the concrete was analyzed. Results show that the freezing construction environment will cause certain damage to the interior of the concrete, and the damage parallel to the heating direction is greater than that in the vertical direction. The damage of the C50 concrete is greater than that of the C70 concrete, and the temperature gradient will aggravate the internal damage of the concrete. The simulated freezing environment will have adverse effects on the compressive strength, splitting tensile strength, chloride ion permeability, and bursting liability of the concrete. The temperature difference has a positive correlation with the performance reduction rate, which becomes more significant for low-strength concrete. The internal microstructure of the concrete block is uneven due to the simulated freezing environment, the concrete structure at the low-temperature end is loose, and the structure at the high-temperature end is dense, resulting in the decrease of the concrete’s performance.
-
Key words:
- freezing method /
- mass concrete /
- bursting liability /
- deep shaft lining /
- ultrasonic measure
-
圖 1 試驗儀器。（a）主控機箱；（b）循環管線和加溫模具
Figure 1. Experiment instrument: (a) main control cabinet; (b) circulation pipeline and heating mold
圖 3 混凝土的抗壓強度和劈裂抗拉強度。（a）抗壓強度；（b）劈裂抗拉強度
Figure 3. Compressive strength and splitting tensile strength of concrete: (a) compressive strength; (b) splitting tensile strength
圖 4 混凝土的氯離子擴散系數。（a）C50；（b）C70
Figure 4. Chloride diffusion coefficient of concrete: (a) C50; (b) C70
圖 5 C50混凝土的掃描電鏡圖片。（a）冷端；（b） 熱端；（c）中溫；（d）標準養護
Figure 5. SEM images of C50 concrete: (a) cold side; (b) hot side; (c) medium temperature; (d) standard curing
圖 6 C70混凝土的掃描電鏡圖片。（a）冷端；（b）熱端；（c）中溫；（d）標準養護
Figure 6. SEM image of C70 concrete: (a) cold side; (b) hot side; (c) medium temperature; (d) standard curing
表 1 P.O 42.5水泥性能指標
Table 1. Main properties of cement
Water mass requirement for normal
consistency/%Initial setting
time/minFinal setting
time/minSpecific surface
area/(m2·kg?1)Soundness Flexural strength/MPa Compressive strength/MPa 3 d 28 d 3 d 28 d 29.2 162 226 392 Qualified 4.9 9.9 27.5 50.0 
下載: 導出CSV
表 2 不同強度等級的混凝土配合比
Table 2. Mix proportions of concrete with different strengths
kg·m?3 Strength grade Cement Fly ash Slag powder Silica fume Sand Stone Water PC* C50 320 80 85 0 673 1077 155 5.82 C70 337 100 108 25 555 1126 140 9.69 Note：* is polycarboxylate superplasticizer for concrete.
下載: 導出CSV
表 3 混凝土在不同條件下的超聲檢測結果
Table 3. Ultrasonic testing results of concrete under different conditions
Strength grade Simulation condition/℃ Direction Amplitude/db Velocity/
(km·s?1)C50 ?5/60 Vertical 101.8 5.68 ?5/60 Parallel 99.8 5.42 Standard curing — 103.6 5.85 ?5/70 Vertical 102.1 5.66 ?5/70 Parallel 100.0 5.33 Standard curing — 104.2 5.94 C70 ?5/60 Vertical 103.1 6.03 ?5/60 Parallel 101.6 5.89 Standard curing — 104.8 6.14 ?5/70 Vertical 103.3 6.08 ?5/70 Parallel 100.2 5.85 Standard curing — 105.3 6.21
下載: 導出CSV
表 4 混凝土在不同溫差模擬條件下的超聲檢測分析結果
Table 4. Analysis results of ultrasonic testing of concrete under different simulation conditions
Strength grade Temperature difference/℃ Relative variation ratio/% Vertical velocity Parallel velocity Vertical amplitude Parallel amplitude C50 ?5/60 2.9 7.4 1.7 3.7 C50 ?5/70 4.7 10.3 2.0 4.2 C70 ?5/60 1.8 4.1 1.6 3.1 C70 ?5/70 2.1 5.8 1.9 4.8
下載: 導出CSV
表 5 混凝土的沖擊傾向性指標
Table 5. Bursting liability indexes of concrete
Group Brittleness Dynamic failure time,
TD/ msImpact energy
index, KEC50 Standard 19.6 480 1.78 C50 ?5/60 ℃ 20.2 410 2.06 C50 ?5/70 ℃ 21.2 380 2.32 C70 Standard 21.9 170 5.81 C70 ?5/60 ℃ 22.8 140 6.32 C70 ?5/70 ℃ 23.5 120 6.55
下載: 導出CSV
www.77susu.com<span id="fpn9h"><noframes id="fpn9h"><span id="fpn9h"></span> <span id="fpn9h"><noframes id="fpn9h"> <th id="fpn9h"></th> <strike id="fpn9h"><noframes id="fpn9h"><strike id="fpn9h"></strike> <th id="fpn9h"><noframes id="fpn9h"> <span id="fpn9h"><video id="fpn9h"></video></span> <ruby id="fpn9h"></ruby> <strike id="fpn9h"><noframes id="fpn9h"><span id="fpn9h"></span> -
參考文獻
[1] Cai M F, Xue D L, Ren F H. Current status and development strategy of metal mines. Chin J Eng, 2019, 41(4): 417蔡美峰, 薛鼎龍, 任奮華. 金屬礦深部開采現狀與發展戰略. 工程科學學報, 2019, 41(4):417 [2] Liu L Y, Ji H G, Wang T, et al. Mechanism of country rock damage and failure in deep shaft excavation under high pore pressure and asymmetric geostress. Chin J Eng, 2020, 42(6): 715劉力源, 紀洪廣, 王濤, 等. 高滲透壓和不對稱圍壓作用下深豎井圍巖損傷破裂機理. 工程科學學報, 2020, 42(6):715 [3] Dong J H, Wu X L, Shi L J, et al. Effect of shallow tunnel construction by horizontal freezing on adjacent orthogonal subgrades. Chin J Rock Mech Eng, 2020, 39(11): 2365董建華, 吳曉磊, 師利君, 等. 水平凍結施工淺埋隧道對鄰近正交路基的作用分析. 巖石力學與工程學報, 2020, 39(11):2365 [4] Zhang J W, Liu S J, Zhang S. Ultrasonic time-frequency characteristics of water-rich fine sand during unidirectional freezing process. Chin J Rock Mech Eng, 2020, 39(5): 1061張基偉, 劉書杰, 張松. 富水細砂單向凍結超聲波時頻特性研究. 巖石力學與工程學報, 2020, 39(5):1061 [5] Gao X J, Li M Y, Zhang J W, et al. Field research on artificial freezing of subway cross passages in water-rich silty clay layers. Chin J Rock Mech Eng, 2021, 40(6): 1267郜新軍, 李銘遠, 張景偉, 等. 富水粉質黏土中地鐵聯絡通道凍結法試驗研究. 巖石力學與工程學報, 2021, 40(6):1267 [6] Ma H Y, Zhu C Q, Zhao P T, et al. Freezing method for rock cross-cut coal uncovering: Aging characteristic of effective freezing distance on injecting liquid nitrogen into coal seam. Adv Civ Eng, 2021: 8870768 [7] Zhang S, Yue Z R, Sun T C, et al. Evolution of ground freezing temperature field under sudden seepage with stable flow rate and discriminate method of seepage. J China Coal Soc, 2020, 45(12): 4017張松, 岳祖潤, 孫鐵成, 等. 突發定滲流作用下凍土溫度場演化規律及判別方法. 煤炭學報, 2020, 45(12):4017 [8] Inada Y, Yokota K. Some studies of low temperature rock strength. Int J Rock Mech Min Sci Geomech Abstr, 1984, 21(3): 145 doi: 10.1016/0148-9062(84)91532-8 [9] Shan R L, Liu W J, Chai G J, et al. Experimental study on the expansion law of local horizontal frozen body under seepage. J China Coal Soc, 2019, 44(Suppl 2): 526單仁亮, 劉偉俊, 柴高竣, 等. 滲流作用下局部水平凍結體擴展規律試驗研究. 煤炭學報, 2019, 44(增刊2): 526 [10] Song Y J, Zhang L T, Ren J X, et al. Creep property and model of red sandstone under low temperature environment. J China Coal Soc, 2020, 45(8): 2795宋勇軍, 張磊濤, 任建喜, 等. 低溫環境下紅砂巖蠕變特性及其模型. 煤炭學報, 2020, 45(8):2795 [11] Yao Z S, Zhao L X, Cheng H, et al. Optimization design and measurement analysis on inter lining of high strength reinforced concrete frozen shaft lining with deep topsoil. J China Coal Soc, 2019, 44(7): 2125姚直書, 趙麗霞, 程樺, 等. 深厚表土層凍結井筒高強鋼筋混凝土內壁設計優化與實測分析. 煤炭學報, 2019, 44(7):2125 [12] Jiao H Z, Sun G D, Chen X M, et al. Development of temperature field of multi circle freezing wall in deep alluvium. J China Coal Soc, 2018, 43(Suppl 2): 443焦華喆, 孫冠東, 陳新明, 等. 深厚沖積層多圈孔凍結壁溫度場發展研究. 煤炭學報, 2018, 43(增刊2): 443 [13] Guan H D, Zhou X M, Xu Y, et al. Calculation of the early thermal stress in freezing vertical shaft lining. Met Mine, 2018(5): 44管華棟, 周曉敏, 徐衍, 等. 凍結立井井壁早期溫度應力計算研究. 金屬礦山, 2018(5):44 [14] Zhou Y Q, Liu W W. Application of granulated copper slag in massive concrete under saline soil environment. Constr Build Mater, 2021, 266: 121165 doi: 10.1016/j.conbuildmat.2020.121165 [15] Azenha M, Kanavaris F, Schlicke D, et al. Recommendations of RILEM TC 287-CCS: Thermo-chemo-mechanical modelling of massive concrete structures towards cracking risk assessment. Mater Struct, 2021, 54(4): 1 [16] Feng C Q, Zhao C, Yu X M, et al. A mathematical model of the expansion evolution of magnesium oxide in mass concrete based on hydration characteristics. Materials, 2021, 14(12): 3162 doi: 10.3390/ma14123162 [17] Bakour A, Ftima M B. Experimental investigations on the asymptotic fracture energy for large mass concrete specimens using wedge splitting test. Constr Build Mater, 2021, 279: 122405 doi: 10.1016/j.conbuildmat.2021.122405 [18] Zhou Y C, Liu J H, Huang S, et al. Performance change of shaft lining concrete under simulated coastal ultra-deep mine environments. Constr Build Mater, 2020, 230: 116909 doi: 10.1016/j.conbuildmat.2019.116909 [19] Liu J H, Zhao L, Ji H G. Influence of initial damage on degradation and deterioration of concrete under sulfate attack. Chin J Eng, 2017, 39(8): 1278劉娟紅, 趙力, 紀洪廣. 初始損傷對混凝土硫酸鹽腐蝕劣化性能的影響. 工程科學學報, 2017, 39(8):1278 [20] Yang L, Yao Z S, Xue W P, et al. Preparation, performance test and microanalysis of hybrid fibers and microexpansive high-performance shaft lining concrete. Constr Build Mater, 2019, 223: 431 doi: 10.1016/j.conbuildmat.2019.06.230 [21] Liu J H, Zhao L, Song S M, et al. Ultrasonic velocity and acoustic emission properties of concrete eroded by sulfate and its damage mechanism. Chin J Eng, 2016, 38(8): 1075劉娟紅, 趙力, 宋少民, 等. 混凝土硫酸鹽腐蝕損傷的聲波與聲發射變化特征及機理. 工程科學學報, 2016, 38(8):1075 [22] Liu J H, Wang Z Q, Ji H G. Performance of shaft lining concrete under the coupling effect of early-age frozen soil pressure and negative temperature. J Univ Sci Technol Beijing, 2014, 36(8): 1000劉娟紅, 王祖琦, 紀洪廣. 早齡期凍結土壓力與負溫耦合作用的井壁混凝土性能. 北京科技大學學報, 2014, 36(8):1000 [23] Zhou Y C, Liu J H, Yang H T, et al. Failure patterns and energy analysis of shaft lining concrete in simulated deep underground environments. J Wuhan Univ Technol Mater Sci Ed, 2020, 35(2): 418 doi: 10.1007/s11595-020-2273-x [24] Liu J H, Zhou Y C, Yang H T, et al. Energy and damage characteristics of shaft lining concrete subjected to impact. J China Coal Soc, 2019, 44(10): 2983劉娟紅, 周昱程, 楊海濤, 等. 沖擊荷載作用下的井壁混凝土能量與損傷特性. 煤炭學報, 2019, 44(10):2983 [25] Liu J H, Zhou Y C, Ji H G. Energy evolution mechanism of shaft wall concrete under uniaxial loading and unloading compression. J China Coal Soc, 2018, 43(12): 3364劉娟紅, 周昱程, 紀洪廣. 單軸加卸載作用下井壁混凝土能量演化機理. 煤炭學報, 2018, 43(12):3364 [26] Zhou Y C, Liu J H, Ji H G, et al. Study on bursting liability of fiber reinforced shaft lining concrete based on temperature and compound salt. Mater Rep, 2019, 33(16): 2671 doi: 10.11896/cldb.18070169周昱程, 劉娟紅, 紀洪廣, 等. 溫度?復合鹽耦合條件下纖維混凝土井壁沖擊傾向性試驗研究. 材料導報, 2019, 33(16):2671 doi: 10.11896/cldb.18070169 [27] Liu J H, Wu R D, Zhou Y C. Experiment of bursting liability of deep underground concrete under complex stress conditions. J China Coal Soc, 2018, 43(1): 79劉娟紅, 吳瑞東, 周昱程. 基于深地復雜應力條件下混凝土沖擊傾向性試驗. 煤炭學報, 2018, 43(1):79 -
點擊查看大圖
圖(6) / 表(5)
計量
- 文章訪問數: 432
- HTML全文瀏覽量: 215
- PDF下載量: 29
- 被引次數: 0
