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研究生:李大振
研究生(外文):Lee, Ta-Chen
論文名稱:片狀砂土水力填築後組構異向性之研究
論文名稱(外文):Research on Anisotropic Behavior of Hydraulic-Filled Sand with Flat Particles
指導教授:李建中李建中引用關係
指導教授(外文):Yan-Chyuan Shiau
學位類別:碩士
校院名稱:國立中央大學
系所名稱:土木工程學系
學門:工程學門
學類:土木工程學類
論文種類:學術論文
論文出版年:1996
畢業學年度:84
語文別:中文
論文頁數:143
中文關鍵詞:水力填築組構異向性沉積角度狀態參數破碎效應
外文關鍵詞:Hydraulic FillsFabric AnisotropicDeposite AngleState ParameterCrushing Effect
相關次數:
  • 被引用被引用:1
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水力填築砂土因其所經歷之壓密時間短,故結構通常較為鬆散,且顆粒在
自重堆積下其組構可能具有異向性,此外,本研究砂土之顆粒大多呈片狀
,故材料的顆粒形狀具有先天的異向性。因此,此種片狀砂土所填築出之
土層,將具有組構的異向性,進而影響其力學行為。
本研究利用試體植膠切片技術,直接對受剪前後之試體,進行微觀組構的
分析及量測,以期能將微觀觀測的結果與巨觀剪力特性,相互印證及討論
。 有關剪力特性方面,乃在探討應力路徑和不同
沉積角度與剪力特性間的關係,因此本研究以水力輸砂儀及角度沉積儀製
作之試體,進行靜態三軸不排水剪力試驗,以獲得各種控制條件下的穩定
狀態線與狀態參數,並以狀態參數來探討試體的不排水剪力性質。另外亦
進行一部份的動力三軸試驗,以探討不同試體準備方式下,砂土的強度與
狀態參數間之關係。 此外,本研究取靜態三軸試驗後的砂土進行篩分析
,以 SEM 及光學顯微鏡來觀察顆粒破碎的大致形式,並對顆粒的破碎進
行量化的步驟,接著亦探討破碎量與各影響因素間的關聯,以期得到一良
好的關係。 綜合所有試驗
分析的結果,可獲致以下的結論: 1.由微觀組構
觀察得知,水力輸砂試體的垂直面顆粒長軸的排列指向水平,濕搗試體不
論在垂直或水平面上,顆粒排列均較隨機,無一定的傾向,故水力輸砂試
體的組構較具異向性,而濕搗試體的組構較不具異向性。此證實了不同的
試體準備方式,將造成不同的組構排列,而使得試體展現不同的強度特性
。 2.在本研究的控制條件下,以水力輸砂法準
備之試體,受剪後皆呈現應變硬化之現象,其行為屬於剪脹性砂土之反應
。而伸張強度小於壓縮強度,且不同的沉積角度,會有不同的穩定狀態線
。故應力路徑與初始組構會對穩定狀態線造成影響。同時沉積角度之不同
,其最大不排水剪力強度會有差異。 3.由
本研究得知,狀態參數與砂土之正規化穩定狀態剪應力及孔隙水壓力參數
間,所具有良好的關係,在不同沉積角度情況下仍然存在,而此關係不受
砂土種類、應力路徑及初始組構的影響。以狀態參數作為比較因子時,可
使複雜多變化的砂土力學特性趨向單純化的結果。
4.組構的排列及載重的施加方式,會對試體的強度造成影響,因此,受剪
過程中顆粒的破碎會對強度造成影響。而破碎量參數(Bg 及 Bt)與狀態
參數有一良好且一致的關係,即狀態參數愈大,破碎量參數愈小,其意義
即代表顆粒破碎所提供強度分量與狀態參數間存有關係。
5.工程分析設計時,須特別注意此片狀砂土強度特性與變形行為之異向性
,因此在設計參數的選用上,應配合試體組構之特性與考量試驗應力之施
加方式,作適當的取捨,才不致於使設計產生偏差。
關鍵詞:水力填築、組構異向性、沉積角度、狀態參數、破碎效應

As a result of generally loose state present in the hydraulic-
filled sand, and the fabric orientation formed during deposition
will cause the soil skeleton tends to be anisotropic. Besides,
most of the particle shape of the testing soil is flatted,
there is inherent anisotropic characteristic in the sand part-
icle. Therefore, the stratum filled by this flat sand shows
fabric anisotro-pic, and the mechanical characteristics of the
soil will be influenced. In this research, the
microanalysis of thin sections on soil fabric is conduct-ed to
observe the arrangement of particles directly under different
conditio -ns. The results observed from microanalysis is used
to verify and discuss the phenomenon of shearing behavior.
As to shearing behavior, the correlation between stress path,
bedding angle and shearing characteristics is investigated. In
this research, a sand-watermixture transportation device and
deposite-angled device was developed toprepare test ing
specimens. A series of static triaxial undrained shear tests
are perform ed using these specimens to find out steady state
line and state parameter. Moreover, use state parameter to
investigate the undrainedshearing characteristics for each
undrained shearing behavior. Besides, part of cyclic
triaxial tests are carried out to investigate the correlation
between strength and state parameter in the sand under sample
preparation methods.
In addition, sieve analysis is used in this research. Therefore,
the ration ofparticles' breakage can be in progress. Then, the
well relationship amongvarious influence factors and breakage
was find out. Besides, the SEM and optical microscope devices
was used to observe the general types of particles'breakage.
Refer to all results obtained, the following conclusions can be
achieved: 1. As
to microfabric observing, the apparent long axis of particles
willorient to horizontal direction in the vertical section of
hydraulic-filledspecimen. However, the particles' arrangement
of moist tamping specimen israndom distribution whatever in the
vertical or horizontal section. This shows the fabric of
hydraulic-filled sand is more anisotropic than moisttamping
specimen. It's proved that difference of fabric orientation of
the testing soil given by various sample preparation methods
will result in a discrepancy of strength characteristic.
2. Under this research condition, hydraulic-filled specimens
appear strain-hardening phenomenon. This action belongs dilate-
sheared response. Besides, the extension strength is lower than
compression strength, and different angle (a) will result in
different steady state line. Therefore, stress pathand initial
fabric affect the position of steady state line. Moreover,
differ-ent a will result in a discrepancy of maximum undrained
shearing strength.3. It's known that state parameter is a
dependent of normalized steady stateshear strength and pore
water pressure parameter. This relationship still exists in
different angle of deposite. Besides, the correlation is
notaffected by sorts of sand, stress path and initial fabric.
Therefore, the complicated soil mechanical characteristics will
be tended to simplicity when we use state parameter to evaluate
it. 4. The orientation of fabric and method of the applied
load will affect the strength of specimen. Therefore,
particles' breakage during shearing willinfluence the strength.
However, breakage parameter ( Bg and Bt ) has good r-elationship
with state parameter. It shows that the breakage parameter is
small with state parameter is large. It means that particle
crushed has good relationship with state parameter.
5. These demonstrate that the anisotropic characteristics of the
testingsoil have significant effect on the shear strength and
deformation behavior,consequently, the fabric orientation and
the direction of applying stress of the specimen should be
considered adequately in the choice of design parameter.
Keywords: Hydraulic Fills, Fabric Anisotropy, Deposite Angle,
State Parameter, Crushing Effect

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