3.2 Compression wave velocity
Compression waves (P-waves) is the first mode of
elastic wave propagation through soil occurring at very
small stain levels [21] This wave travels effectively
through solids and fluids, and are dependent on the
bulk stiffness (B) and the shear stiffness (G) as
described in Table 2. P-wave velocity is primarily
dependent on the porosity, the fluid bulk stiffness, and
the material comprising the soil particles. It is not
sensitive to the shear stiffness of the soil matrix. It is
excellent for monitoring changes in pore fluid
compressibility, especially in single phase materials
(i.e. rock, concrete) and biocemented soils having
sufficient cementation quantity (Vp > 1500 m s-1) [2].
However, measurement of P-wave velocity in
unbounded and lightly cemented soils does not
correlate directly with strength unless the soil matrix
maintains a constant saturation level and/or until
sufficient cementation has occurred such that the
particle matrix compressibility significantly exceeds
that of water [2].
3.3 Shear wave velocity
Many studies reported the non-destructive test for
measuring shear wave velocity and shear modulus [22-
28] but few researches are found in biological soil
improvement applications. In this article, we described
the example of shear wave velocity for strength
measurement in loose sand before and after
biocementation process. This example is presented and
discussed in Section 4. Shear waves (S-waves), the
second mode of propagation, in which the direction of
particle motion is perpendicular to the direction of
propagation [21] and it is recently used for measuring
the relative strength in soil [22-28]. Advantages of this
application are a non-destructive examination and are
capable to measure the soil strength in function of
time. Thus, it can be applied in the field for measuring
the changes of ground improvement conditions in the
long period.
3.3.1 Piezo-ceramic bender element and operating
sensors
Element tests involve sending elastic waves
through a specimen to cause transient perturbation to
the particles, of which the resistance encountered by
the induced vibration is translated as stiffness of the
material. The elastic waves can be compression or
shear waves depending on the direction of the wave
movement [29]. Elements generating S-waves are
called bender elements (BEs) because of their shape of
movement. The principle of BEs is based on the
properties of piezoelectric materials as they distort or
bend when subjected to a change in voltage and
generate a voltage when are distorted or bent.
BEs consist of two thin piezo-ceramic plates that
are mounted together, separated by an electrode
surface and bounded by two further electrode surfaces.
The two piezoceramic sheets may be polarized in the
same or opposite directions by wiring either in parallel
or series, depending on whether an electrical signal is
to be transmitted or received. In a series connected
element (Fig. 2a) the wires are connected to the outer
electrode surfaces and the two piezoceramic plates are
polarized in opposite directions. In a parallel connected
element (Fig. 2b) the wires are connected to both the
outer electrode surfaces and the centre electrode (by
careful grinding away of a small portion of the
3.2 Compression wave velocity
Compression waves (P-waves) is the first mode of
elastic wave propagation through soil occurring at very
small stain levels [21] This wave travels effectively
through solids and fluids, and are dependent on the
bulk stiffness (B) and the shear stiffness (G) as
described in Table 2. P-wave velocity is primarily
dependent on the porosity, the fluid bulk stiffness, and
the material comprising the soil particles. It is not
sensitive to the shear stiffness of the soil matrix. It is
excellent for monitoring changes in pore fluid
compressibility, especially in single phase materials
(i.e. rock, concrete) and biocemented soils having
sufficient cementation quantity (Vp > 1500 m s-1) [2].
However, measurement of P-wave velocity in
unbounded and lightly cemented soils does not
correlate directly with strength unless the soil matrix
maintains a constant saturation level and/or until
sufficient cementation has occurred such that the
particle matrix compressibility significantly exceeds
that of water [2].
3.3 Shear wave velocity
Many studies reported the non-destructive test for
measuring shear wave velocity and shear modulus [22-
28] but few researches are found in biological soil
improvement applications. In this article, we described
the example of shear wave velocity for strength
measurement in loose sand before and after
biocementation process. This example is presented and
discussed in Section 4. Shear waves (S-waves), the
second mode of propagation, in which the direction of
particle motion is perpendicular to the direction of
propagation [21] and it is recently used for measuring
the relative strength in soil [22-28]. Advantages of this
application are a non-destructive examination and are
capable to measure the soil strength in function of
time. Thus, it can be applied in the field for measuring
the changes of ground improvement conditions in the
long period.
3.3.1 Piezo-ceramic bender element and operating
sensors
Element tests involve sending elastic waves
through a specimen to cause transient perturbation to
the particles, of which the resistance encountered by
the induced vibration is translated as stiffness of the
material. The elastic waves can be compression or
shear waves depending on the direction of the wave
movement [29]. Elements generating S-waves are
called bender elements (BEs) because of their shape of
movement. The principle of BEs is based on the
properties of piezoelectric materials as they distort or
bend when subjected to a change in voltage and
generate a voltage when are distorted or bent.
BEs consist of two thin piezo-ceramic plates that
are mounted together, separated by an electrode
surface and bounded by two further electrode surfaces.
The two piezoceramic sheets may be polarized in the
same or opposite directions by wiring either in parallel
or series, depending on whether an electrical signal is
to be transmitted or received. In a series connected
element (Fig. 2a) the wires are connected to the outer
electrode surfaces and the two piezoceramic plates are
polarized in opposite directions. In a parallel connected
element (Fig. 2b) the wires are connected to both the
outer electrode surfaces and the centre electrode (by
careful grinding away of a small portion of the
การแปล กรุณารอสักครู่..

3.2 Compression wave velocity
Compression waves (P-waves) is the first mode of
elastic wave propagation through soil occurring at very
small stain levels [21] This wave travels effectively
through solids and fluids, and are dependent on the
bulk stiffness (B) and the shear stiffness (G) as
described in Table 2. P-wave velocity is primarily
dependent on the porosity, the fluid bulk stiffness, and
the material comprising the soil particles. It is not
sensitive to the shear stiffness of the soil matrix. It is
excellent for monitoring changes in pore fluid
compressibility, especially in single phase materials
(i.e. rock, concrete) and biocemented soils having
sufficient cementation quantity (Vp > 1500 m s-1) [2].
However, measurement of P-wave velocity in
unbounded and lightly cemented soils does not
correlate directly with strength unless the soil matrix
maintains a constant saturation level and/or until
sufficient cementation has occurred such that the
particle matrix compressibility significantly exceeds
that of water [2].
3.3 Shear wave velocity
Many studies reported the non-destructive test for
measuring shear wave velocity and shear modulus [22-
28] but few researches are found in biological soil
improvement applications. In this article, we described
the example of shear wave velocity for strength
measurement in loose sand before and after
biocementation process. This example is presented and
discussed in Section 4. Shear waves (S-waves), the
second mode of propagation,ซึ่งทิศทางของ
การเคลื่อนที่ของอนุภาคตั้งฉากกับทิศทางของ
, [ 21 ] และมันเพิ่งจะใช้วัด
ความแข็งแรงสัมพัทธ์ในดิน [ นี้ ] ข้อดีของโปรแกรมนี้คือการตรวจสอบแบบไม่ทำลายและ
สามารถวัดความแข็งแรงของดินในการทำงาน
ครั้ง ดังนั้นจึงสามารถใช้ในเขตวัด
the changes of ground improvement conditions in the
long period.
3.3.1 Piezo-ceramic bender element and operating
sensors
Element tests involve sending elastic waves
through a specimen to cause transient perturbation to
the particles, of which the resistance encountered by
the induced vibration is translated as stiffness of the
material. The elastic waves can be compression or
คลื่นแรงเฉือนขึ้นอยู่กับทิศทางการเคลื่อนไหวของคลื่น
[ 29 ] องค์ประกอบการสร้าง s-waves
เรียกว่าเป็นองค์ประกอบ Bender ( BES ) เนื่องจากรูปร่างของพวกเขา
การเคลื่อนไหว หลักการคือจะขึ้นอยู่กับคุณสมบัติของวัสดุเพียโซอิเล็กทริก
เช่นที่พวกเขาบิดเบือนหรือ
งอเมื่อถูกเปลี่ยนแรงดัน
สร้างแรงดันเมื่อมีการบิดเบี้ยวคดงอ .
คือประกอบด้วยสองบางจานเซรามิก Piezo ที่
ติดตั้งด้วยกัน โดยแยกเป็นสองขั้ว
พื้นผิวและล้อมรอบด้วยพื้นผิวขั้วไฟฟ้าเพิ่มเติม .
2 piezoceramic แผ่นอาจจะขั้วในทิศทางเดียวกันหรือตรงข้ามด้วย
หรือชุดสายไฟทั้งในแบบคู่ขนาน ขึ้นอยู่กับว่าเป็นสัญญาณไฟฟ้าคือ
ที่จะส่งหรือ ที่ได้รับ ในชุดเชื่อม
( รูปธาตุ2A ) สายไฟที่เชื่อมต่อกับพื้นผิวด้านนอก
ขั้วไฟฟ้า และสอง piezoceramic จาน
ขั้วในทิศทางตรงกันข้าม ในแบบคู่ขนานที่เชื่อมต่อองค์ประกอบ ( รูปที่ 2B
) สายจะเชื่อมต่อกับทั้ง
นอกขั้วพื้นผิวและศูนย์ขั้ว (
ระวังคัฟ แล้วส่วนขนาดเล็กของ
การแปล กรุณารอสักครู่..
