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No.45 (1998/12) >

Title :広範な応力下における一次元圧縮による石灰質砂の粒子破砕
Title alternative :Particle breakage of calcareous sands under vertical stress in one-dimensional compression
Authors :新城, 俊也
島川, 真由美
Authors alternative :Shinjo, Toshiya
Shimakawa, Mayumi
Issue Date :1-Dec-1998
Abstract :圧縮応力による粒子破砕の程度と圧縮性に及ぼす粒子破砕の影響を把握するため2種類の石灰質砂について乾燥状態と水侵状態で50MPaまでの一次元圧縮試験を実施した。主な結果は以下のようである。(1) 圧縮性は細粒な砂より粗粒の砂において大きい。また, 圧縮性に及ぼす水侵の影響は小さい。(2) 圧縮試験におけるe-log σ_v関係には降伏点みられ, この降伏圧縮応力を境に圧縮指数C_cは増大する。同様に粒子破砕も顕著となる。(3) 圧縮応力の増加による粒子破砕に伴って粒径0.075mm以下の細粒分が増加するが, ある程度細粒分が増加すると, 圧縮応力の増加に伴う粒子破砕量の増加割合は低減する。(4) 破砕係数BcはMarsalの方法による粒子破砕量B_MおよびLeslieの方法による粒子破砕量ΔFと相関関係にある。(5) 破砕係数B_cの増加に対して圧縮指数C_cが急激に増加することから, わずかの粒子破砕で圧縮性が顕著とならことが認められた。
A series of one-dimensional compressive tests has been performed on skeletal calcareous sands in order to investigate a degree of particle breakage under compressive stress. The tests were carried out on dried and saturated samples in each sand up to vertical stresses of 50MPa. The amount of particle breakage is evaluated with the index Bc defined as the ratio of percentage of particles of sand after test finer than D_<10> of original sand to percentage of particles finer than D_<10> of original sand. The compressibility of sand is measured by the compression index C_c calculated as the mean slope of the void ratio -log (vertical stress) curve for each increment of vertical stress. Test results show that there is little effect of saturation on particle crushing and compression of sands. According to the change of gradation curves with applied stress, it is found that the ratio of the increasing in the amount of particle breakage to the increasing in applied stress is decreased with the increasing in fine grain content finer than 0.075mm due to particle crushing. The value of C_c is rapidly increases with the increasing in B_c. It is concluded that the compression is mainly due to the breakage of particle under a wide range of vertical applied stress.
Type Local :紀要論文
ISSN :0370-4246
Publisher :琉球大学農学部
URI :http://hdl.handle.net/20.500.12000/3687
Citation :琉球大学農学部学術報告 = The Science Bulletin of the Faculty of Agriculture. University of the Ryukyus no.45 p.141 -148
Appears in Collections:No.45 (1998/12)

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