The purpose of the study is to obtain a cement grout with improved performance. The grout mixes of the present study contain cement, ultra-fine slag （UFS）, super plasticizer and water. Properties like flowability, b...The purpose of the study is to obtain a cement grout with improved performance. The grout mixes of the present study contain cement, ultra-fine slag （UFS）, super plasticizer and water. Properties like flowability, bleeding, compressive strength and shrinkage of cement grouts have been studied. Rheological parameters were also studied in order to explain the grout workability. The results show that, cement replacement with slag in grouts could reduce bleeding substantially without affecting the workability of the mixes. Introduction of slag enhanced the compressive strength and reduced shrinkage reasonably. Ultra-fine slag can be used as a supplementary cementitious material in cementitious grouts in order to improve the grout behavior.展开更多
Grout injection is used for sealing or strengthening the ground in order to prevent water entrance or any failure after excavation.There are many methods of grouting.Permeation grouting is one of the most common types...Grout injection is used for sealing or strengthening the ground in order to prevent water entrance or any failure after excavation.There are many methods of grouting.Permeation grouting is one of the most common types in which the grout material is injected to the pore spaces of the ground.In grouting operations,the grout quality is important to achieve the best results.There are four main characteristics for a grout mixture including bleeding,setting time,strength,and viscosity.In this paper,we try to build some efficient grouting mixtures with different water to cement ratios considering these characteristics.The ingredients of grout mixtures built in this study are cement,water,bentonite,and some chemical additives such as sodium silicate,sodium carbonate,and triethanolamine(TEA).The grout mixtures are prepared for both of the sealing and strengthening purposes for a structural project.Effect of each abovementioned ingredient is profoundly investigated.Since each ingredient may have positive or negative aspect,an optimization of appropriate amount of each ingredient is determined.The optimization is based on 200 grout mixture samples with different percentages of ingredients.Finally,some of these grout mixtures are chosen for the introduced project.It should be mentioned that grouting operations depend on various factors such as pressure of injection,ground structure and grain size of soils.However,quality of a grout can be helpful to make an injection easier and reasonable.For example,during the injection,a wrong estimated setting time can destroy the injected grout by washing the grout or setting early which prevents grouting.This paper tries to show some tests in easy way to achieve a desirable sample of grout.展开更多
Proper room and pillar sizes are both critical factors for safe mining and high ore recovery rate in shrinkage stoping mining of underground metal mines. The rock masses of Tangdan copper mine of China are fractured, ...Proper room and pillar sizes are both critical factors for safe mining and high ore recovery rate in shrinkage stoping mining of underground metal mines. The rock masses of Tangdan copper mine of China are fractured, which needs much reinforcement and support prior to mining. Cement-sodium silicate grout technology was selected, then its related parameters such as grout pressure, diffusion radius and time were calculated and proposed. In order to test the effect of the pressured grout in the fractured No.4 ore block, field experiments were conducted. To optimize stoping configuration, three-dimensional numerical simulation with ANSYS and FLAC 3 D softwares was proposed. The results show that the drilling porosity and mechanical properties of the rock masses are increased obviously. After grout, ore recovery rate is increased by 10.2 % employing the newly designed stoping configuration compared with the previous. Last, analyzed from the surface movements, roof subsidence and the maximum principal stress of the pillars, the mining safety is probable of being ensured.展开更多
文摘The purpose of the study is to obtain a cement grout with improved performance. The grout mixes of the present study contain cement, ultra-fine slag （UFS）, super plasticizer and water. Properties like flowability, bleeding, compressive strength and shrinkage of cement grouts have been studied. Rheological parameters were also studied in order to explain the grout workability. The results show that, cement replacement with slag in grouts could reduce bleeding substantially without affecting the workability of the mixes. Introduction of slag enhanced the compressive strength and reduced shrinkage reasonably. Ultra-fine slag can be used as a supplementary cementitious material in cementitious grouts in order to improve the grout behavior.
文摘Grout injection is used for sealing or strengthening the ground in order to prevent water entrance or any failure after excavation.There are many methods of grouting.Permeation grouting is one of the most common types in which the grout material is injected to the pore spaces of the ground.In grouting operations,the grout quality is important to achieve the best results.There are four main characteristics for a grout mixture including bleeding,setting time,strength,and viscosity.In this paper,we try to build some efficient grouting mixtures with different water to cement ratios considering these characteristics.The ingredients of grout mixtures built in this study are cement,water,bentonite,and some chemical additives such as sodium silicate,sodium carbonate,and triethanolamine(TEA).The grout mixtures are prepared for both of the sealing and strengthening purposes for a structural project.Effect of each abovementioned ingredient is profoundly investigated.Since each ingredient may have positive or negative aspect,an optimization of appropriate amount of each ingredient is determined.The optimization is based on 200 grout mixture samples with different percentages of ingredients.Finally,some of these grout mixtures are chosen for the introduced project.It should be mentioned that grouting operations depend on various factors such as pressure of injection,ground structure and grain size of soils.However,quality of a grout can be helpful to make an injection easier and reasonable.For example,during the injection,a wrong estimated setting time can destroy the injected grout by washing the grout or setting early which prevents grouting.This paper tries to show some tests in easy way to achieve a desirable sample of grout.
基金Projects(51374034,51674012) supported by the National Natural Science Foundation of ChinaProject(2013BAB02B05) supported by the China National Science and Technology Support Program during the 12th Five-Year Plan Period
文摘Proper room and pillar sizes are both critical factors for safe mining and high ore recovery rate in shrinkage stoping mining of underground metal mines. The rock masses of Tangdan copper mine of China are fractured, which needs much reinforcement and support prior to mining. Cement-sodium silicate grout technology was selected, then its related parameters such as grout pressure, diffusion radius and time were calculated and proposed. In order to test the effect of the pressured grout in the fractured No.4 ore block, field experiments were conducted. To optimize stoping configuration, three-dimensional numerical simulation with ANSYS and FLAC 3 D softwares was proposed. The results show that the drilling porosity and mechanical properties of the rock masses are increased obviously. After grout, ore recovery rate is increased by 10.2 % employing the newly designed stoping configuration compared with the previous. Last, analyzed from the surface movements, roof subsidence and the maximum principal stress of the pillars, the mining safety is probable of being ensured.
